AbstractSqlTester fails to build query for expression TRIM(string)

When running the following test in SqlOperatorTest,

f.checkString("trim(' aAa ')", "aAa", "VARCHAR(5) NOT NULL");

it throws "java.lang.StringIndexOutOfBoundsException: begin 8, end 21, length 17".

The expression "trim(' aAa ')" will be parsed into "trim(both ' ' from ' aAa ')" (call it TrimFuncCall).
However, when building the above query that extracts all literals as columns in an underlying select(in AbstractSqlTester.buildQuery2()), the space literal in TrimFuncCall will be extracted, which doesn't exist in the original expression "trim(' aAa ')". We just need to extract "' aAa '" in this case, and get

select trim(p0) from (values (' aAa ')) as t(p0)