There is potentially unexpected behaviour of the indexOf method of the DBDictionary class (org.apache.openjpa.jdbc.sql.DBDictionary) when a start index is specified but the search string is not found.
When a start index is specified (say "N"), the search target string has the first N characters removed, the search performed (by INSTR in the default case), this is reduced by 1 to make it 0-indexed and then crucially the start index in added to the result.
In Oracle, if the search term is not found, INSTR returns 0. If a start index is supplied, this is then added and 1 is taken away, so the "result of indexOf" will be "start index - 1" if the search string is not found. It may not be obvious whether, once a query is run, a number represents a successful match or not.
I would expect the case where the string is not found to return 0 or -1, depending on the index base. I think it is misleading for this to return a positive integer if the string is not found.
Since you cannot tell whether the string will be matched at the time the query is constructed, it may be difficult to find a fix for this.