Method isWallSign

src/main/java/org/bukkit/material/Sign.java:38–40

Check if this sign is attached to a wall @return true if this sign is attached to a wall, false if set on top of a block

()

     *     a block
     */
    public boolean isWallSign() {
        return getItemType() == Material.LEGACY_WALL_SIGN;
    }

    /**
     * Gets the face that this block is attached on