#1397 StringToString should ignore method references

[Ben Manes]

The rule should not be triggered when a toString() is passed as a method reference. In general a method reference is preferred to an ad hoc lambda by having shorter byte code and potential for future JVM optimizations.

void log(Supplier<string> msg) { ... }
log("abc"::toString); // fails rule
log(() -> "abc"); // passes rule</string>

[Andreas Dangel]

This will be fixed with PMD 5.3.4.

Commit: https://github.com/pmd/pmd/commit/3abfc2fccb1ab76f2ec4f8f64c252f81adb1949c