@Override
public void neighborChanged(IBlockState state, World world, BlockPos pos, Block block, BlockPos fromPos) {
if (world.getBlockState(fromPos).getBlock() == жидкостьКотораяПриплыла) {
}
}
@Override
public void onBlockAdded(World world, BlockPos pos, IBlockState state) {
targetBlocks.add(world.getBlockState(pos.offset(EnumFacing.UP)).getBlock());
targetBlocks.add(world.getBlockState(pos.offset(EnumFacing.DOWN)).getBlock());
targetBlocks.add(world.getBlockState(pos.offset(EnumFacing.EAST)).getBlock());
targetBlocks.add(world.getBlockState(pos.offset(EnumFacing.WEST)).getBlock());
targetBlocks.add(world.getBlockState(pos.offset(EnumFacing.SOUTH)).getBlock());
targetBlocks.add(world.getBlockState(pos.offset(EnumFacing.NORTH)).getBlock());
if (targetBlocks.constains(другая_жидкость)) {
}
// *Или короче
// Arrays.stream(EnumFacing.values()).map(pos::offset)
// .filter(targetPos -> world.getBlockState(targetPos) == другая_жидкость).findAny()
// .ifPresent(findedPos -> {
//
// });
}