private static final Set<Block> EFFECTIVE_ON = Sets.newHashSet(new Block[] { Blocks.ACTIVATOR_RAIL, Blocks.COAL_ORE, Blocks.COBBLESTONE, Blocks.DETECTOR_RAIL, Blocks.DIAMOND_BLOCK, Blocks.DIAMOND_ORE, Blocks.DOUBLE_STONE_SLAB, Blocks.GOLDEN_RAIL, Blocks.GOLD_BLOCK, Blocks.GOLD_ORE, Blocks.ICE, Blocks.IRON_BLOCK, Blocks.IRON_ORE, Blocks.LAPIS_BLOCK, Blocks.LAPIS_ORE, Blocks.LIT_REDSTONE_ORE, Blocks.MOSSY_COBBLESTONE, Blocks.NETHERRACK, Blocks.PACKED_ICE, Blocks.RAIL, Blocks.REDSTONE_ORE, Blocks.SANDSTONE, Blocks.RED_SANDSTONE, Blocks.STONE, Blocks.STONE_SLAB, Blocks.STONE_BUTTON, Blocks.STONE_PRESSURE_PLATE} );
Lovely Mojang code there...