presto-main/src/main/java/io/prestosql/sql/gen/JoinFilterFunctionCompiler.java/JoinFilterFunctionCompiler/toString
class JoinFilterFunctionCompiler:        @Override
        public String toString()
        {
            return toStringHelper(this)
                    .add("filter", filter)
                    .add("leftBlocksSize", leftBlocksSize)
                    .toString();
        }