diff --git a/src/api/java/appeng/api/networking/IGrid.java b/src/api/java/appeng/api/networking/IGrid.java
index d06ba8d7e..0f2fbfb1c 100644
--- a/src/api/java/appeng/api/networking/IGrid.java
+++ b/src/api/java/appeng/api/networking/IGrid.java
@@ -24,6 +24,8 @@
 package appeng.api.networking;
 
 
+import javax.annotation.Nonnull;
+
 import appeng.api.networking.events.MENetworkEvent;
 import appeng.api.util.IReadOnlyCollection;
 
@@ -43,7 +45,8 @@ public interface IGrid
 	 *
 	 * @return the IGridCache you requested.
 	 */
-	<C extends IGridCache> C getCache( Class<? extends IGridCache> iface );
+	@Nonnull
+	<C extends IGridCache> C getCache( @Nonnull Class<? extends IGridCache> iface );
 
 	/**
 	 * Post an event into the network event bus.
@@ -52,7 +55,8 @@ public interface IGrid
 	 *
 	 * @return returns ev back to original poster
 	 */
-	MENetworkEvent postEvent( MENetworkEvent ev );
+	@Nonnull
+	MENetworkEvent postEvent( @Nonnull MENetworkEvent ev );
 
 	/**
 	 * Post an event into the network event bus, but direct it at a single node.
@@ -61,7 +65,8 @@ public interface IGrid
 	 *
 	 * @return returns ev back to original poster
 	 */
-	MENetworkEvent postEventTo( IGridNode node, MENetworkEvent ev );
+	@Nonnull
+	MENetworkEvent postEventTo( @Nonnull IGridNode node, @Nonnull MENetworkEvent ev );
 
 	/**
 	 * get a list of the diversity of classes, you can use this to better detect which machines your interested in,
@@ -69,6 +74,7 @@ public interface IGrid
 	 *
 	 * @return IReadOnlyCollection of all available host types (Of Type IGridHost).
 	 */
+	@Nonnull
 	IReadOnlyCollection<Class<? extends IGridHost>> getMachinesClasses();
 
 	/**
@@ -78,11 +84,13 @@ public interface IGrid
 	 *
 	 * @return IMachineSet of all nodes belonging to hosts of specified class.
 	 */
-	IMachineSet getMachines( Class<? extends IGridHost> gridHostClass );
+	@Nonnull
+	IMachineSet getMachines( @Nonnull Class<? extends IGridHost> gridHostClass );
 
 	/**
 	 * @return IReadOnlyCollection for all nodes on the network, node visitors are preferred.
 	 */
+	@Nonnull
 	IReadOnlyCollection<IGridNode> getNodes();
 
 	/**
@@ -93,5 +101,6 @@ public interface IGrid
 	/**
 	 * @return the node considered the pivot point of the grid.
 	 */
+	@Nonnull
 	IGridNode getPivot();
 }
\ No newline at end of file
diff --git a/src/api/java/appeng/api/networking/IGridBlock.java b/src/api/java/appeng/api/networking/IGridBlock.java
index 87baf84de..d6e1822aa 100644
--- a/src/api/java/appeng/api/networking/IGridBlock.java
+++ b/src/api/java/appeng/api/networking/IGridBlock.java
@@ -26,6 +26,10 @@ package appeng.api.networking;
 
 import java.util.EnumSet;
 
+import javax.annotation.Nonnegative;
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
 import net.minecraft.item.ItemStack;
 import net.minecraft.util.EnumFacing;
 
@@ -49,6 +53,7 @@ public interface IGridBlock
 	 *
 	 * @return ae/t to use.
 	 */
+	@Nonnegative
 	double getIdlePowerUsage();
 
 	/**
@@ -56,10 +61,11 @@ public interface IGridBlock
 	 *
 	 * @return Set of flags for this IGridBlock
 	 */
+	@Nonnull
 	EnumSet<GridFlags> getFlags();
 
 	/**
-	 * generally speaking you will return true for this, the one exception is buses, or worm holes where the node
+	 * Generally speaking you will return true for this, the one exception is buses, or worm holes where the node
 	 * represents something that isn't a real connection in the world, but rather one represented internally to the
 	 * block.
 	 *
@@ -68,37 +74,46 @@ public interface IGridBlock
 	boolean isWorldAccessible();
 
 	/**
+	 * Must not return when {@link #isWorldAccessible()} is true.
+	 * Otherwise the behavior is unspecified.
+	 *
 	 * @return current location of this node
 	 */
+	@Nonnull
 	DimensionalCoord getLocation();
 
 	/**
 	 * @return Transparent, or a valid color, NULL IS NOT A VALID RETURN
 	 */
+	@Nonnull
 	AEColor getGridColor();
 
 	/**
 	 * Notifies your IGridBlock that changes were made to your connections
 	 */
-	void onGridNotification( GridNotification notification );
+	void onGridNotification( @Nonnull GridNotification notification );
 
 	/**
 	 * Update Blocks network/connection/booting status. grid,
 	 *
 	 * @param grid grid
 	 * @param channelsInUse used channels
+	 * @deprecated to be removed in rv7
 	 */
+	@Deprecated
 	void setNetworkStatus( IGrid grid, int channelsInUse );
 
 	/**
 	 * Determine which sides of the block can be connected too, only used when isWorldAccessible returns true, not used
 	 * for {@link IPart} implementations.
 	 */
+	@Nonnull
 	EnumSet<EnumFacing> getConnectableSides();
 
 	/**
 	 * @return the IGridHost for the node, this will be an IGridPart or a TileEntity generally speaking.
 	 */
+	@Nonnull
 	IGridHost getMachine();
 
 	/**
@@ -111,5 +126,6 @@ public interface IGridBlock
 	 *
 	 * @return the render item stack to use to render this node, null is valid, and will not show this node.
 	 */
+	@Nullable
 	ItemStack getMachineRepresentation();
 }
diff --git a/src/api/java/appeng/api/networking/IGridCache.java b/src/api/java/appeng/api/networking/IGridCache.java
index e692f2372..634ed1b6a 100644
--- a/src/api/java/appeng/api/networking/IGridCache.java
+++ b/src/api/java/appeng/api/networking/IGridCache.java
@@ -24,6 +24,9 @@
 package appeng.api.networking;
 
 
+import javax.annotation.Nonnull;
+
+
 /**
  * Allows you to create a network wise service, AE2 uses these for providing
  * item, spatial, and tunnel services.
@@ -50,7 +53,7 @@ public interface IGridCache
 	 * @param gridNode removed from that grid
 	 * @param machine to be removed machine
 	 */
-	void removeNode( IGridNode gridNode, IGridHost machine );
+	void removeNode( @Nonnull IGridNode gridNode, @Nonnull IGridHost machine );
 
 	/**
 	 * informs you cache that a machine was added to the grid.
@@ -62,7 +65,7 @@ public interface IGridCache
 	 * @param gridNode added to grid node
 	 * @param machine to be added machine
 	 */
-	void addNode( IGridNode gridNode, IGridHost machine );
+	void addNode( @Nonnull IGridNode gridNode, @Nonnull IGridHost machine );
 
 	/**
 	 * Called when a grid splits into two grids, AE will call a split as it
@@ -71,7 +74,7 @@ public interface IGridCache
 	 *
 	 * @param destinationStorage storage which receives half of old grid
 	 */
-	void onSplit( IGridStorage destinationStorage );
+	void onSplit( @Nonnull IGridStorage destinationStorage );
 
 	/**
 	 * Called when two grids merge into one, AE will call a join as it
@@ -80,12 +83,12 @@ public interface IGridCache
 	 *
 	 * @param sourceStorage old storage
 	 */
-	void onJoin( IGridStorage sourceStorage );
+	void onJoin( @Nonnull IGridStorage sourceStorage );
 
 	/**
 	 * Called when saving changes,
 	 *
 	 * @param destinationStorage storage
 	 */
-	void populateGridStorage( IGridStorage destinationStorage );
+	void populateGridStorage( @Nonnull IGridStorage destinationStorage );
 }
diff --git a/src/api/java/appeng/api/networking/IGridCacheRegistry.java b/src/api/java/appeng/api/networking/IGridCacheRegistry.java
index b54df8dae..47601abf5 100644
--- a/src/api/java/appeng/api/networking/IGridCacheRegistry.java
+++ b/src/api/java/appeng/api/networking/IGridCacheRegistry.java
@@ -24,7 +24,9 @@
 package appeng.api.networking;
 
 
-import java.util.HashMap;
+import java.util.Map;
+
+import javax.annotation.Nonnull;
 
 
 /**
@@ -38,14 +40,14 @@ public interface IGridCacheRegistry
 	 *
 	 * @param iface grid cache class
 	 */
-	void registerGridCache( Class<? extends IGridCache> iface, Class<? extends IGridCache> implementation );
+	void registerGridCache( @Nonnull Class<? extends IGridCache> iface, @Nonnull Class<? extends IGridCache> implementation );
 
 	/**
 	 * requests a new INSTANCE of a grid cache for use, used internally
 	 *
 	 * @param grid grid
 	 *
-	 * @return a new HashMap of IGridCaches from the registry, called from IGrid when constructing a new grid.
+	 * @return a new Map of IGridCaches from the registry, called from IGrid when constructing a new grid.
 	 */
-	HashMap<Class<? extends IGridCache>, IGridCache> createCacheInstance( IGrid grid );
+	Map<Class<? extends IGridCache>, IGridCache> createCacheInstance( IGrid grid );
 }
diff --git a/src/api/java/appeng/api/networking/IGridConnection.java b/src/api/java/appeng/api/networking/IGridConnection.java
index 20cbcbe49..85ff26690 100644
--- a/src/api/java/appeng/api/networking/IGridConnection.java
+++ b/src/api/java/appeng/api/networking/IGridConnection.java
@@ -24,6 +24,8 @@
 package appeng.api.networking;
 
 
+import javax.annotation.Nonnull;
+
 import appeng.api.util.AEPartLocation;
 
 
@@ -45,6 +47,7 @@ public interface IGridConnection
 	 *
 	 * @return the IGridNode which represents the opposite side of the connection.
 	 */
+	@Nonnull
 	IGridNode getOtherSide( IGridNode gridNode );
 
 	/**
@@ -54,6 +57,7 @@ public interface IGridConnection
 	 *
 	 * @return the direction of the connection, only valid for in world connections.
 	 */
+	@Nonnull
 	AEPartLocation getDirection( IGridNode gridNode );
 
 	/**
@@ -65,11 +69,13 @@ public interface IGridConnection
 	/**
 	 * @return node A
 	 */
+	@Nonnull
 	IGridNode a();
 
 	/**
 	 * @return node B
 	 */
+	@Nonnull
 	IGridNode b();
 
 	/**
diff --git a/src/api/java/appeng/api/networking/IGridConnectionVisitor.java b/src/api/java/appeng/api/networking/IGridConnectionVisitor.java
index 1842589e0..84cd12f91 100644
--- a/src/api/java/appeng/api/networking/IGridConnectionVisitor.java
+++ b/src/api/java/appeng/api/networking/IGridConnectionVisitor.java
@@ -24,6 +24,9 @@
 package appeng.api.networking;
 
 
+import javax.annotation.Nonnull;
+
+
 public interface IGridConnectionVisitor extends IGridVisitor
 {
 
@@ -32,5 +35,5 @@ public interface IGridConnectionVisitor extends IGridVisitor
 	 *
 	 * @param n the connection.
 	 */
-	void visitConnection( IGridConnection n );
+	void visitConnection( @Nonnull IGridConnection n );
 }
diff --git a/src/api/java/appeng/api/networking/IGridHelper.java b/src/api/java/appeng/api/networking/IGridHelper.java
index 40a766909..b79b6a76b 100644
--- a/src/api/java/appeng/api/networking/IGridHelper.java
+++ b/src/api/java/appeng/api/networking/IGridHelper.java
@@ -24,12 +24,14 @@
 package appeng.api.networking;
 
 
+import javax.annotation.Nonnull;
+
 import appeng.api.exceptions.FailedConnectionException;
 
 
 /**
  * A helper responsible for creating new {@link IGridNode}, {@link IGridConnection} or potentially similar tasks.
- * 
+ *
  * @author yueh
  * @version rv5
  * @since rv5
@@ -39,7 +41,7 @@ public interface IGridHelper
 
 	/**
 	 * Create a grid node for your {@link IGridHost}
-	 * 
+	 *
 	 * The passed {@link IGridBlock} represents the definition for properties like connectable sides.
 	 * Refer to its documentation for further details.
 	 *
@@ -47,18 +49,20 @@ public interface IGridHelper
 	 *
 	 * @return grid node of block
 	 */
-	IGridNode createGridNode( IGridBlock block );
+	@Nonnull
+	IGridNode createGridNode( @Nonnull IGridBlock block );
 
 	/**
 	 * Create a direct connection between two {@link IGridNode}.
-	 * 
+	 *
 	 * This will be considered as having a distance of 1, regardless of the location of both nodes.
-	 * 
+	 *
 	 * @param a to be connected gridnode
 	 * @param b to be connected gridnode
 	 *
 	 * @throws appeng.api.exceptions.FailedConnectionException
 	 */
-	IGridConnection createGridConnection( IGridNode a, IGridNode b ) throws FailedConnectionException;
+	@Nonnull
+	IGridConnection createGridConnection( @Nonnull IGridNode a, @Nonnull IGridNode b ) throws FailedConnectionException;
 
 }
\ No newline at end of file
diff --git a/src/api/java/appeng/api/networking/IGridHost.java b/src/api/java/appeng/api/networking/IGridHost.java
index bd272c895..3738d778b 100644
--- a/src/api/java/appeng/api/networking/IGridHost.java
+++ b/src/api/java/appeng/api/networking/IGridHost.java
@@ -24,6 +24,9 @@
 package appeng.api.networking;
 
 
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
 import net.minecraft.tileentity.TileEntity;
 
 import appeng.api.parts.IPart;
@@ -49,7 +52,8 @@ public interface IGridHost
 	 * @return a new IGridNode, create these with
 	 * AEApi.INSTANCE().createGridNode( MyIGridBlock )
 	 */
-	IGridNode getGridNode( AEPartLocation dir );
+	@Nullable
+	IGridNode getGridNode( @Nonnull AEPartLocation dir );
 
 	/**
 	 * Determines how cables render when they connect to this block. Priority is
@@ -57,7 +61,8 @@ public interface IGridHost
 	 *
 	 * @param dir direction
 	 */
-	AECableType getCableConnectionType( AEPartLocation dir );
+	@Nonnull
+	AECableType getCableConnectionType( @Nonnull AEPartLocation dir );
 
 	/**
 	 * break this host, its violating security rules, just break your block, or part.
diff --git a/src/api/java/appeng/api/networking/IGridMultiblock.java b/src/api/java/appeng/api/networking/IGridMultiblock.java
index 7c3844bb7..f99b1b174 100644
--- a/src/api/java/appeng/api/networking/IGridMultiblock.java
+++ b/src/api/java/appeng/api/networking/IGridMultiblock.java
@@ -26,6 +26,8 @@ package appeng.api.networking;
 
 import java.util.Iterator;
 
+import javax.annotation.Nonnull;
+
 
 /**
  * An extension of IGridBlock, only means something when your getFlags() contains REQUIRE_CHANNEL, when done properly it
@@ -40,5 +42,6 @@ public interface IGridMultiblock extends IGridBlock
 	 *
 	 * @return an iterator that will iterate all the nodes for the multiblock. ( read-only iterator expected. )
 	 */
+	@Nonnull
 	Iterator<IGridNode> getMultiblockNodes();
 }
diff --git a/src/api/java/appeng/api/networking/IGridNode.java b/src/api/java/appeng/api/networking/IGridNode.java
index 667db3876..729c420f3 100644
--- a/src/api/java/appeng/api/networking/IGridNode.java
+++ b/src/api/java/appeng/api/networking/IGridNode.java
@@ -26,6 +26,8 @@ package appeng.api.networking;
 
 import java.util.EnumSet;
 
+import javax.annotation.Nonnull;
+
 import net.minecraft.nbt.NBTTagCompound;
 import net.minecraft.world.World;
 
@@ -50,7 +52,7 @@ public interface IGridNode
 	 *
 	 * @param visitor visitor
 	 */
-	void beginVisit( IGridVisitor visitor );
+	void beginVisit( @Nonnull IGridVisitor visitor );
 
 	/**
 	 * inform the node that your IGridBlock has changed its internal state, and force the node to update.
@@ -68,6 +70,7 @@ public interface IGridNode
 	 *
 	 * @return grid host
 	 */
+	@Nonnull
 	IGridHost getMachine();
 
 	/**
@@ -75,6 +78,7 @@ public interface IGridNode
 	 *
 	 * @return grid
 	 */
+	@Nonnull
 	IGrid getGrid();
 
 	/**
@@ -86,11 +90,13 @@ public interface IGridNode
 	/**
 	 * @return the world the node is located in
 	 */
+	@Nonnull
 	World getWorld();
 
 	/**
 	 * @return a set of the connected sides, INTERNAL represents an invisible connection
 	 */
+	@Nonnull
 	EnumSet<AEPartLocation> getConnectedSides();
 
 	/**
@@ -98,11 +104,13 @@ public interface IGridNode
 	 *
 	 * @return grid connections
 	 */
+	@Nonnull
 	IReadOnlyCollection<IGridConnection> getConnections();
 
 	/**
 	 * @return the IGridBlock for this node
 	 */
+	@Nonnull
 	IGridBlock getGridBlock();
 
 	/**
@@ -122,7 +130,7 @@ public interface IGridNode
 	 * @param name nbt name
 	 * @param nodeData to be loaded data
 	 */
-	void loadFromNBT( String name, NBTTagCompound nodeData );
+	void loadFromNBT( @Nonnull String name, @Nonnull NBTTagCompound nodeData );
 
 	/**
 	 * this should be called for each node you maintain, you can save all your nodes to the same tag with different
@@ -131,7 +139,7 @@ public interface IGridNode
 	 * @param name nbt name
 	 * @param nodeData to be saved data
 	 */
-	void saveToNBT( String name, NBTTagCompound nodeData );
+	void saveToNBT( @Nonnull String name, @Nonnull NBTTagCompound nodeData );
 
 	/**
 	 * @return if the node's channel requirements are currently met, use this for display purposes, use isActive for
@@ -146,7 +154,7 @@ public interface IGridNode
 	 *
 	 * @return true if has flag
 	 */
-	boolean hasFlag( GridFlags flag );
+	boolean hasFlag( @Nonnull GridFlags flag );
 
 	/**
 	 * @return the ownerID this represents the person who placed the node.
diff --git a/src/api/java/appeng/api/networking/IGridStorage.java b/src/api/java/appeng/api/networking/IGridStorage.java
index 0f9e9b7b5..f380ffe43 100644
--- a/src/api/java/appeng/api/networking/IGridStorage.java
+++ b/src/api/java/appeng/api/networking/IGridStorage.java
@@ -24,6 +24,8 @@
 package appeng.api.networking;
 
 
+import javax.annotation.Nonnull;
+
 import net.minecraft.nbt.NBTTagCompound;
 
 
@@ -33,6 +35,7 @@ public interface IGridStorage
 	/**
 	 * @return an NBTTagCompound that can be read, and written too.
 	 */
+	@Nonnull
 	NBTTagCompound dataObject();
 
 	/**
diff --git a/src/api/java/appeng/api/networking/IGridVisitor.java b/src/api/java/appeng/api/networking/IGridVisitor.java
index 41ac4f475..d9386fdea 100644
--- a/src/api/java/appeng/api/networking/IGridVisitor.java
+++ b/src/api/java/appeng/api/networking/IGridVisitor.java
@@ -24,6 +24,9 @@
 package appeng.api.networking;
 
 
+import javax.annotation.Nonnull;
+
+
 /**
  * Simple Visitor pattern access to network nodes.
  */
@@ -39,5 +42,5 @@ public interface IGridVisitor
 	 *
 	 * @return true to continue visiting nodes beyond this node.
 	 */
-	boolean visitNode( IGridNode n );
+	boolean visitNode( @Nonnull IGridNode n );
 }
diff --git a/src/api/java/appeng/api/networking/IMachineSet.java b/src/api/java/appeng/api/networking/IMachineSet.java
index 7d57b52cf..5d19ee18a 100644
--- a/src/api/java/appeng/api/networking/IMachineSet.java
+++ b/src/api/java/appeng/api/networking/IMachineSet.java
@@ -24,6 +24,8 @@
 package appeng.api.networking;
 
 
+import javax.annotation.Nonnull;
+
 import appeng.api.util.IReadOnlyCollection;
 
 
@@ -33,5 +35,6 @@ public interface IMachineSet extends IReadOnlyCollection<IGridNode>
 	/**
 	 * @return the machine class for this set.
 	 */
+	@Nonnull
 	Class<? extends IGridHost> getMachineClass();
 }
diff --git a/src/api/java/appeng/api/networking/crafting/ICraftingCallback.java b/src/api/java/appeng/api/networking/crafting/ICraftingCallback.java
index 096b72260..f86780b55 100644
--- a/src/api/java/appeng/api/networking/crafting/ICraftingCallback.java
+++ b/src/api/java/appeng/api/networking/crafting/ICraftingCallback.java
@@ -24,6 +24,9 @@
 package appeng.api.networking.crafting;
 
 
+import javax.annotation.Nonnull;
+
+
 public interface ICraftingCallback
 {
 
@@ -32,5 +35,5 @@ public interface ICraftingCallback
 	 *
 	 * @param job - final job
 	 */
-	void calculationComplete( ICraftingJob job );
+	void calculationComplete( @Nonnull ICraftingJob job );
 }
diff --git a/src/api/java/appeng/api/networking/energy/IAEPowerStorage.java b/src/api/java/appeng/api/networking/energy/IAEPowerStorage.java
index 7cb1ac10f..30220d9b8 100644
--- a/src/api/java/appeng/api/networking/energy/IAEPowerStorage.java
+++ b/src/api/java/appeng/api/networking/energy/IAEPowerStorage.java
@@ -24,6 +24,8 @@
 package appeng.api.networking.energy;
 
 
+import javax.annotation.Nonnull;
+
 import appeng.api.config.AccessRestriction;
 import appeng.api.config.Actionable;
 
@@ -42,7 +44,7 @@ public interface IAEPowerStorage extends IEnergySource
 	 *
 	 * @return amount of power which was unable to be stored
 	 */
-	double injectAEPower( double amt, Actionable mode );
+	double injectAEPower( double amt, @Nonnull Actionable mode );
 
 	/**
 	 * @return the current maximum power ( this can change :P )
@@ -67,5 +69,6 @@ public interface IAEPowerStorage extends IEnergySource
 	 *
 	 * @return access restriction what the network can do
 	 */
+	@Nonnull
 	AccessRestriction getPowerFlow();
 }
\ No newline at end of file
diff --git a/src/api/java/appeng/api/networking/energy/IEnergyGrid.java b/src/api/java/appeng/api/networking/energy/IEnergyGrid.java
index 666b35321..fa4efa71b 100644
--- a/src/api/java/appeng/api/networking/energy/IEnergyGrid.java
+++ b/src/api/java/appeng/api/networking/energy/IEnergyGrid.java
@@ -24,6 +24,9 @@
 package appeng.api.networking.energy;
 
 
+import javax.annotation.Nonnegative;
+import javax.annotation.Nonnull;
+
 import appeng.api.config.Actionable;
 import appeng.api.networking.IGridCache;
 import appeng.api.networking.events.MENetworkPowerStatusChange;
@@ -38,17 +41,20 @@ public interface IEnergyGrid extends IGridCache, IEnergySource, IEnergyGridProvi
 	/**
 	 * @return the current calculated idle energy drain each tick, is used internally to drain power for each tick.
 	 */
+	@Nonnegative
 	double getIdlePowerUsage();
 
 	/**
 	 * @return the average power drain over the past 10 ticks, includes idle usage during this time, and all use of
 	 * extractPower.
 	 */
+	@Nonnegative
 	double getAvgPowerUsage();
 
 	/**
 	 * @return the average energy injected into the system per tick, for the last 10 ticks.
 	 */
+	@Nonnegative
 	double getAvgPowerInjection();
 
 	/**
@@ -79,13 +85,15 @@ public interface IEnergyGrid extends IGridCache, IEnergySource, IEnergyGridProvi
 	 *
 	 * @return the amount of power that the network has OVER the limit.
 	 */
-	double injectPower( double amt, Actionable mode );
+	@Nonnegative
+	double injectPower( @Nonnegative double amt, @Nonnull Actionable mode );
 
 	/**
 	 * this is should be considered an estimate, and not relied upon for real calculations.
 	 *
 	 * @return estimated available power.
 	 */
+	@Nonnegative
 	double getStoredPower();
 
 	/**
@@ -93,6 +101,7 @@ public interface IEnergyGrid extends IGridCache, IEnergySource, IEnergyGridProvi
 	 *
 	 * @return estimated available power.
 	 */
+	@Nonnegative
 	double getMaxStoredPower();
 
 	/**
@@ -101,5 +110,6 @@ public interface IEnergyGrid extends IGridCache, IEnergySource, IEnergyGridProvi
 	 *
 	 * @return Amount of power required to charge the grid, in AE.
 	 */
-	double getEnergyDemand( double maxRequired );
+	@Nonnegative
+	double getEnergyDemand( @Nonnegative double maxRequired );
 }
diff --git a/src/api/java/appeng/api/networking/energy/IEnergySource.java b/src/api/java/appeng/api/networking/energy/IEnergySource.java
index b1185dfa2..45bdbc807 100644
--- a/src/api/java/appeng/api/networking/energy/IEnergySource.java
+++ b/src/api/java/appeng/api/networking/energy/IEnergySource.java
@@ -24,6 +24,9 @@
 package appeng.api.networking.energy;
 
 
+import javax.annotation.Nonnegative;
+import javax.annotation.Nonnull;
+
 import appeng.api.config.Actionable;
 import appeng.api.config.PowerMultiplier;
 
@@ -39,5 +42,6 @@ public interface IEnergySource
 	 *
 	 * @return returns extracted power.
 	 */
-	double extractAEPower( double amt, Actionable mode, PowerMultiplier usePowerMultiplier );
+	@Nonnegative
+	double extractAEPower( @Nonnegative double amt, @Nonnull Actionable mode, @Nonnull PowerMultiplier usePowerMultiplier );
 }
diff --git a/src/api/java/appeng/api/networking/energy/IEnergyWatcher.java b/src/api/java/appeng/api/networking/energy/IEnergyWatcher.java
index a75871470..809a92e8c 100644
--- a/src/api/java/appeng/api/networking/energy/IEnergyWatcher.java
+++ b/src/api/java/appeng/api/networking/energy/IEnergyWatcher.java
@@ -24,6 +24,9 @@
 package appeng.api.networking.energy;
 
 
+import javax.annotation.Nonnegative;
+
+
 /**
  * DO NOT IMPLEMENT.
  *
@@ -39,7 +42,7 @@ public interface IEnergyWatcher
 	 * @param amount
 	 * @return true, if successfully added.
 	 */
-	boolean add( double amount );
+	boolean add( @Nonnegative double amount );
 
 	/**
 	 * Remove a specific threshold from the watcher.
@@ -47,7 +50,7 @@ public interface IEnergyWatcher
 	 * @param amount
 	 * @return true, if successfully removed.
 	 */
-	boolean remove( double amount );
+	boolean remove( @Nonnegative double amount );
 
 	/**
 	 * Removes all thresholds and resets the watcher to a clean state.
diff --git a/src/api/java/appeng/api/networking/energy/IEnergyWatcherHost.java b/src/api/java/appeng/api/networking/energy/IEnergyWatcherHost.java
index 5f5237f0d..e9b7c81c2 100644
--- a/src/api/java/appeng/api/networking/energy/IEnergyWatcherHost.java
+++ b/src/api/java/appeng/api/networking/energy/IEnergyWatcherHost.java
@@ -24,6 +24,9 @@
 package appeng.api.networking.energy;
 
 
+import javax.annotation.Nonnull;
+
+
 public interface IEnergyWatcherHost
 {
 
@@ -33,12 +36,12 @@ public interface IEnergyWatcherHost
 	 *
 	 * @param newWatcher new watcher
 	 */
-	void updateWatcher( IEnergyWatcher newWatcher );
+	void updateWatcher( @Nonnull IEnergyWatcher newWatcher );
 
 	/**
 	 * Called when a threshold is crossed.
 	 *
 	 * @param energyGrid grid
 	 */
-	void onThresholdPass( IEnergyGrid energyGrid );
+	void onThresholdPass( @Nonnull IEnergyGrid energyGrid );
 }
diff --git a/src/api/java/appeng/api/networking/pathing/IPathingGrid.java b/src/api/java/appeng/api/networking/pathing/IPathingGrid.java
index f9a592eee..8dc84df58 100644
--- a/src/api/java/appeng/api/networking/pathing/IPathingGrid.java
+++ b/src/api/java/appeng/api/networking/pathing/IPathingGrid.java
@@ -24,6 +24,8 @@
 package appeng.api.networking.pathing;
 
 
+import javax.annotation.Nonnull;
+
 import appeng.api.networking.IGridCache;
 
 
@@ -39,6 +41,7 @@ public interface IPathingGrid extends IGridCache
 	 * @return the controller state of the network, useful if you want to
 	 * require a controller for a feature.
 	 */
+	@Nonnull
 	ControllerState getControllerState();
 
 	/**
diff --git a/src/api/java/appeng/api/networking/security/IActionHost.java b/src/api/java/appeng/api/networking/security/IActionHost.java
index 02cd2c413..908e17445 100644
--- a/src/api/java/appeng/api/networking/security/IActionHost.java
+++ b/src/api/java/appeng/api/networking/security/IActionHost.java
@@ -24,6 +24,8 @@
 package appeng.api.networking.security;
 
 
+import javax.annotation.Nonnull;
+
 import appeng.api.networking.IGridNode;
 
 
@@ -38,5 +40,6 @@ public interface IActionHost
 	 * @return the the gridnode that actions from this IGridHost are preformed
 	 * by.
 	 */
+	@Nonnull
 	IGridNode getActionableNode();
 }
diff --git a/src/api/java/appeng/api/networking/security/ISecurityGrid.java b/src/api/java/appeng/api/networking/security/ISecurityGrid.java
index 9dd0ad09a..77b49366d 100644
--- a/src/api/java/appeng/api/networking/security/ISecurityGrid.java
+++ b/src/api/java/appeng/api/networking/security/ISecurityGrid.java
@@ -24,6 +24,9 @@
 package appeng.api.networking.security;
 
 
+import javax.annotation.Nonnegative;
+import javax.annotation.Nonnull;
+
 import net.minecraft.entity.player.EntityPlayer;
 
 import appeng.api.config.SecurityPermissions;
@@ -46,7 +49,7 @@ public interface ISecurityGrid extends IGridCache
 	 *
 	 * @return true if the player has permissions.
 	 */
-	boolean hasPermission( EntityPlayer player, SecurityPermissions perm );
+	boolean hasPermission( @Nonnull EntityPlayer player, @Nonnull SecurityPermissions perm );
 
 	/**
 	 * Check if a player has permissions.
@@ -56,7 +59,7 @@ public interface ISecurityGrid extends IGridCache
 	 *
 	 * @return true if the player has permissions.
 	 */
-	boolean hasPermission( int playerID, SecurityPermissions perm );
+	boolean hasPermission( @Nonnegative int playerID, @Nonnull SecurityPermissions perm );
 
 	/**
 	 * @return PlayerID of the admin, or owner, this is the person who placed the security block.
diff --git a/src/api/java/appeng/api/networking/security/ISecurityProvider.java b/src/api/java/appeng/api/networking/security/ISecurityProvider.java
index 049d2e640..6cd6a2d5f 100644
--- a/src/api/java/appeng/api/networking/security/ISecurityProvider.java
+++ b/src/api/java/appeng/api/networking/security/ISecurityProvider.java
@@ -25,7 +25,7 @@ package appeng.api.networking.security;
 
 
 import java.util.EnumSet;
-import java.util.HashMap;
+import java.util.Map;
 
 import appeng.api.config.SecurityPermissions;
 
@@ -48,7 +48,7 @@ public interface ISecurityProvider
 	 *
 	 * @param playerPerms player permissions
 	 */
-	void readPermissions( HashMap<Integer, EnumSet<SecurityPermissions>> playerPerms );
+	void readPermissions( Map<Integer, EnumSet<SecurityPermissions>> playerPerms );
 
 	/**
 	 * @return is security on or off?
diff --git a/src/api/java/appeng/api/networking/security/ISecurityRegistry.java b/src/api/java/appeng/api/networking/security/ISecurityRegistry.java
index 77ed8df33..29c4f12ee 100644
--- a/src/api/java/appeng/api/networking/security/ISecurityRegistry.java
+++ b/src/api/java/appeng/api/networking/security/ISecurityRegistry.java
@@ -26,6 +26,8 @@ package appeng.api.networking.security;
 
 import java.util.EnumSet;
 
+import javax.annotation.Nonnull;
+
 import appeng.api.config.SecurityPermissions;
 
 
@@ -41,5 +43,5 @@ public interface ISecurityRegistry
 	 * @param playerID player id
 	 * @param permissions permissions of player
 	 */
-	void addPlayer( int playerID, EnumSet<SecurityPermissions> permissions );
+	void addPlayer( int playerID, @Nonnull EnumSet<SecurityPermissions> permissions );
 }
diff --git a/src/api/java/appeng/api/networking/ticking/IGridTickable.java b/src/api/java/appeng/api/networking/ticking/IGridTickable.java
index c5d103509..9fe4ac792 100644
--- a/src/api/java/appeng/api/networking/ticking/IGridTickable.java
+++ b/src/api/java/appeng/api/networking/ticking/IGridTickable.java
@@ -24,6 +24,8 @@
 package appeng.api.networking.ticking;
 
 
+import javax.annotation.Nonnull;
+
 import appeng.api.networking.IGridNode;
 
 
@@ -45,18 +47,18 @@ public interface IGridTickable
 	 */
 
 	/**
-	 * You can return null, if you wish to tick using MC's ticking mechanism, or
-	 * you can return a valid TickingRequest to tell AE a guide for which type
-	 * of responsiveness your device wants.
+	 * Return a valid TickingRequest to tell AE a guide for which type of
+	 * responsiveness your device wants.
 	 *
-	 * this will be called for your tile any time your tile changes grids, this
+	 * This will be called for your tile any time your tile changes grids, this
 	 * can happen at any time, so if your using the sleep feature you may wish
 	 * to preserve your sleep, in the result of this method. or you can simply
 	 * reset it.
 	 *
-	 * @return null or a valid new TickingRequest
+	 * @return a valid new TickingRequest
 	 */
-	TickingRequest getTickingRequest( IGridNode node );
+	@Nonnull
+	TickingRequest getTickingRequest( @Nonnull IGridNode node );
 
 	/**
 	 * AE lets you adjust your tick rate based on the results of your tick, if
@@ -67,11 +69,12 @@ public interface IGridTickable
 	 *
 	 * Note: this is never called if you return null from getTickingRequest.
 	 *
-	 * @param TicksSinceLastCall the number of world ticks that were skipped since your last
+	 * @param ticksSinceLastCall the number of world ticks that were skipped since your last
 	 * tick, you can use this to adjust speed of processing or adjust
 	 * your tick rate.
 	 *
 	 * @return tick rate adjustment.
 	 */
-	TickRateModulation tickingRequest( IGridNode node, int TicksSinceLastCall );
+	@Nonnull
+	TickRateModulation tickingRequest( @Nonnull IGridNode node, int ticksSinceLastCall );
 }
diff --git a/src/api/java/appeng/api/networking/ticking/ITickManager.java b/src/api/java/appeng/api/networking/ticking/ITickManager.java
index 6c5d7de82..5294cdb4b 100644
--- a/src/api/java/appeng/api/networking/ticking/ITickManager.java
+++ b/src/api/java/appeng/api/networking/ticking/ITickManager.java
@@ -24,6 +24,8 @@
 package appeng.api.networking.ticking;
 
 
+import javax.annotation.Nonnull;
+
 import appeng.api.networking.IGridCache;
 import appeng.api.networking.IGridNode;
 
@@ -42,7 +44,7 @@ public interface ITickManager extends IGridCache
 	 *
 	 * @param node gridnode
 	 */
-	boolean alertDevice( IGridNode node );
+	boolean alertDevice( @Nonnull IGridNode node );
 
 	/**
 	 * disables ticking for your device.
@@ -51,7 +53,7 @@ public interface ITickManager extends IGridCache
 	 *
 	 * @return if the call was successful.
 	 */
-	boolean sleepDevice( IGridNode node );
+	boolean sleepDevice( @Nonnull IGridNode node );
 
 	/**
 	 * enables ticking for your device, undoes a sleepDevice call.
@@ -60,5 +62,5 @@ public interface ITickManager extends IGridCache
 	 *
 	 * @return if the call was successful.
 	 */
-	boolean wakeDevice( IGridNode node );
+	boolean wakeDevice( @Nonnull IGridNode node );
 }
diff --git a/src/main/java/appeng/helpers/PlayerSecurityWrapper.java b/src/main/java/appeng/helpers/PlayerSecurityWrapper.java
index 27889752a..a79e4207d 100644
--- a/src/main/java/appeng/helpers/PlayerSecurityWrapper.java
+++ b/src/main/java/appeng/helpers/PlayerSecurityWrapper.java
@@ -20,7 +20,6 @@ package appeng.helpers;
 
 
 import java.util.EnumSet;
-import java.util.HashMap;
 import java.util.Map;
 
 import appeng.api.config.SecurityPermissions;
@@ -32,7 +31,7 @@ public class PlayerSecurityWrapper implements ISecurityRegistry
 
 	private final Map<Integer, EnumSet<SecurityPermissions>> target;
 
-	public PlayerSecurityWrapper( final HashMap<Integer, EnumSet<SecurityPermissions>> playerPerms )
+	public PlayerSecurityWrapper( final Map<Integer, EnumSet<SecurityPermissions>> playerPerms )
 	{
 		this.target = playerPerms;
 	}
diff --git a/src/main/java/appeng/me/cache/TickManagerCache.java b/src/main/java/appeng/me/cache/TickManagerCache.java
index ab5760dcd..0f3e0a359 100644
--- a/src/main/java/appeng/me/cache/TickManagerCache.java
+++ b/src/main/java/appeng/me/cache/TickManagerCache.java
@@ -22,6 +22,8 @@ package appeng.me.cache;
 import java.util.HashMap;
 import java.util.PriorityQueue;
 
+import com.google.common.base.Preconditions;
+
 import net.minecraft.crash.CrashReport;
 import net.minecraft.crash.CrashReportCategory;
 import net.minecraft.util.ReportedException;
@@ -156,25 +158,26 @@ public class TickManagerCache implements ITickManager
 	{
 		if( machine instanceof IGridTickable )
 		{
-			final TickingRequest tr = ( (IGridTickable) machine ).getTickingRequest( gridNode );
-			if( tr != null )
+			final IGridTickable tickable = ( (IGridTickable) machine );
+			final TickingRequest tr = tickable.getTickingRequest( gridNode );
+
+			Preconditions.checkNotNull( tr );
+
+			final TickTracker tt = new TickTracker( tr, gridNode, (IGridTickable) machine, this.currentTick, this );
+
+			if( tr.canBeAlerted )
 			{
-				final TickTracker tt = new TickTracker( tr, gridNode, (IGridTickable) machine, this.currentTick, this );
+				this.alertable.put( gridNode, tt );
+			}
 
-				if( tr.canBeAlerted )
-				{
-					this.alertable.put( gridNode, tt );
-				}
-
-				if( tr.isSleeping )
-				{
-					this.sleeping.put( gridNode, tt );
-				}
-				else
-				{
-					this.awake.put( gridNode, tt );
-					this.addToQueue( tt );
-				}
+			if( tr.isSleeping )
+			{
+				this.sleeping.put( gridNode, tt );
+			}
+			else
+			{
+				this.awake.put( gridNode, tt );
+				this.addToQueue( tt );
 			}
 		}
 	}
@@ -200,6 +203,8 @@ public class TickManagerCache implements ITickManager
 	@Override
 	public boolean alertDevice( final IGridNode node )
 	{
+		Preconditions.checkNotNull( node );
+
 		final TickTracker tt = this.alertable.get( node );
 		if( tt == null )
 		{
@@ -226,6 +231,8 @@ public class TickManagerCache implements ITickManager
 	@Override
 	public boolean sleepDevice( final IGridNode node )
 	{
+		Preconditions.checkNotNull( node );
+
 		if( this.awake.containsKey( node ) )
 		{
 			final TickTracker gt = this.awake.get( node );
@@ -241,6 +248,8 @@ public class TickManagerCache implements ITickManager
 	@Override
 	public boolean wakeDevice( final IGridNode node )
 	{
+		Preconditions.checkNotNull( node );
+
 		if( this.sleeping.containsKey( node ) )
 		{
 			final TickTracker gt = this.sleeping.get( node );
diff --git a/src/main/java/appeng/tile/misc/TileSecurityStation.java b/src/main/java/appeng/tile/misc/TileSecurityStation.java
index b8de0c164..abc309e34 100644
--- a/src/main/java/appeng/tile/misc/TileSecurityStation.java
+++ b/src/main/java/appeng/tile/misc/TileSecurityStation.java
@@ -21,8 +21,8 @@ package appeng.tile.misc;
 
 import java.io.IOException;
 import java.util.EnumSet;
-import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import io.netty.buffer.ByteBuf;
 
@@ -316,7 +316,7 @@ public class TileSecurityStation extends AENetworkTile implements ITerminalHost,
 	}
 
 	@Override
-	public void readPermissions( final HashMap<Integer, EnumSet<SecurityPermissions>> playerPerms )
+	public void readPermissions( final Map<Integer, EnumSet<SecurityPermissions>> playerPerms )
 	{
 		final IPlayerRegistry pr = AEApi.instance().registries().players();