fixed mistake

BauSystem_15/src/de/steamwar/bausystem/utils/FlatteningWrapper15.java

@@ -159,7 +159,7 @@ public class FlatteningWrapper15 implements FlatteningWrapper {
 
                     BaseBlock block = clipboard.getFullBlock(blockVector3);
                     String blockName = block.toString().toLowerCase();
-                    return blockName.equals("minecraft:water") || blocks.contains(blockName);
+                    return !blockName.equals("minecraft:water") || blocks.contains(blockName);
                 }
 
                 @Nullable