presto-spi/src/main/java/io/prestosql/spi/type/MapType.java/KeyWrapper/equals
class KeyWrapper:        @Override
        public boolean equals(Object obj)
        {
            if (obj == null || !getClass().equals(obj.getClass())) {
                return false;
            }
            KeyWrapper other = (KeyWrapper) obj;
            return type.equalTo(this.block, this.position, other.getBlock(), other.getPosition());
        }