CodeQL library for Java
codeql/java-all 0.3.5 (changelog, source)

Member predicate RegexString::sourceCharacter

Holds if the ith character of the string is represented between offsets start (inclusive) and end (exclusive) in the source code of this literal. This only gives correct results if the literal is written as a normal single-line string literal; without compile-time concatenation involved.

predicate sourceCharacter(int pos, int start, int end)