SPIGOT-5716: Clarify documentation of MultipleFacing

src/main/java/org/bukkit/craftbukkit/block/data/CraftMultipleFacing.java

@@ -10,12 +10,20 @@ public abstract class CraftMultipleFacing extends CraftBlockData implements Mult
 
     @Override
     public boolean hasFace(org.bukkit.block.BlockFace face) {
-        return get(FACES[face.ordinal()]);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        return get(state);
     }
 
     @Override
     public void setFace(org.bukkit.block.BlockFace face, boolean has) {
-        set(FACES[face.ordinal()], has);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        set(state, has);
     }
 
     @Override

src/main/java/org/bukkit/craftbukkit/block/impl/CraftChorusFruit.java

@@ -21,12 +21,20 @@ public final class CraftChorusFruit extends org.bukkit.craftbukkit.block.data.Cr
 
     @Override
     public boolean hasFace(org.bukkit.block.BlockFace face) {
-        return get(FACES[face.ordinal()]);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        return get(state);
     }
 
     @Override
     public void setFace(org.bukkit.block.BlockFace face, boolean has) {
-        set(FACES[face.ordinal()], has);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        set(state, has);
     }
 
     @Override

src/main/java/org/bukkit/craftbukkit/block/impl/CraftCobbleWall.java

@@ -21,12 +21,20 @@ public final class CraftCobbleWall extends org.bukkit.craftbukkit.block.data.Cra
 
     @Override
     public boolean hasFace(org.bukkit.block.BlockFace face) {
-        return get(FACES[face.ordinal()]);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        return get(state);
     }
 
     @Override
     public void setFace(org.bukkit.block.BlockFace face, boolean has) {
-        set(FACES[face.ordinal()], has);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        set(state, has);
     }
 
     @Override

src/main/java/org/bukkit/craftbukkit/block/impl/CraftFence.java

@@ -21,12 +21,20 @@ public final class CraftFence extends org.bukkit.craftbukkit.block.data.CraftBlo
 
     @Override
     public boolean hasFace(org.bukkit.block.BlockFace face) {
-        return get(FACES[face.ordinal()]);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        return get(state);
     }
 
     @Override
     public void setFace(org.bukkit.block.BlockFace face, boolean has) {
-        set(FACES[face.ordinal()], has);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        set(state, has);
     }
 
     @Override

src/main/java/org/bukkit/craftbukkit/block/impl/CraftFire.java

@@ -40,12 +40,20 @@ public final class CraftFire extends org.bukkit.craftbukkit.block.data.CraftBloc
 
     @Override
     public boolean hasFace(org.bukkit.block.BlockFace face) {
-        return get(FACES[face.ordinal()]);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        return get(state);
     }
 
     @Override
     public void setFace(org.bukkit.block.BlockFace face, boolean has) {
-        set(FACES[face.ordinal()], has);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        set(state, has);
     }
 
     @Override

src/main/java/org/bukkit/craftbukkit/block/impl/CraftHugeMushroom.java

@@ -21,12 +21,20 @@ public final class CraftHugeMushroom extends org.bukkit.craftbukkit.block.data.C
 
     @Override
     public boolean hasFace(org.bukkit.block.BlockFace face) {
-        return get(FACES[face.ordinal()]);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        return get(state);
     }
 
     @Override
     public void setFace(org.bukkit.block.BlockFace face, boolean has) {
-        set(FACES[face.ordinal()], has);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        set(state, has);
     }
 
     @Override

src/main/java/org/bukkit/craftbukkit/block/impl/CraftIronBars.java

@@ -21,12 +21,20 @@ public final class CraftIronBars extends org.bukkit.craftbukkit.block.data.Craft
 
     @Override
     public boolean hasFace(org.bukkit.block.BlockFace face) {
-        return get(FACES[face.ordinal()]);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        return get(state);
     }
 
     @Override
     public void setFace(org.bukkit.block.BlockFace face, boolean has) {
-        set(FACES[face.ordinal()], has);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        set(state, has);
     }
 
     @Override

src/main/java/org/bukkit/craftbukkit/block/impl/CraftStainedGlassPane.java

@@ -21,12 +21,20 @@ public final class CraftStainedGlassPane extends org.bukkit.craftbukkit.block.da
 
     @Override
     public boolean hasFace(org.bukkit.block.BlockFace face) {
-        return get(FACES[face.ordinal()]);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        return get(state);
     }
 
     @Override
     public void setFace(org.bukkit.block.BlockFace face, boolean has) {
-        set(FACES[face.ordinal()], has);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        set(state, has);
     }
 
     @Override

src/main/java/org/bukkit/craftbukkit/block/impl/CraftTripwire.java

@@ -49,12 +49,20 @@ public final class CraftTripwire extends org.bukkit.craftbukkit.block.data.Craft
 
     @Override
     public boolean hasFace(org.bukkit.block.BlockFace face) {
-        return get(FACES[face.ordinal()]);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        return get(state);
     }
 
     @Override
     public void setFace(org.bukkit.block.BlockFace face, boolean has) {
-        set(FACES[face.ordinal()], has);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        set(state, has);
     }
 
     @Override

src/main/java/org/bukkit/craftbukkit/block/impl/CraftVine.java

@@ -21,12 +21,20 @@ public final class CraftVine extends org.bukkit.craftbukkit.block.data.CraftBloc
 
     @Override
     public boolean hasFace(org.bukkit.block.BlockFace face) {
-        return get(FACES[face.ordinal()]);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        return get(state);
     }
 
     @Override
     public void setFace(org.bukkit.block.BlockFace face, boolean has) {
-        set(FACES[face.ordinal()], has);
+        net.minecraft.server.BlockStateBoolean state = FACES[face.ordinal()];
+        if (state == null) {
+            throw new IllegalArgumentException("Non-allowed face " + face + ". Check MultipleFacing.getAllowedFaces.");
+        }
+        set(state, has);
     }
 
     @Override