[java] FinalFieldCouldBeStatic false positive with non-static synchronized block (regression in 6.48, worked with 6.47)

[hgschmie]

Affects PMD Version: 6.48

Rule: FinalFieldCouldBeStatic

Please provide the rule name and a link to the rule documentation: https://pmd.github.io/latest/pmd_rules_java_design.html#finalfieldcouldbestatic

Description:

6.48 flags objects that are only used for synchronization incorrectly

Code Sample demonstrating the issue:

class foo {
    private final Object[] lock = new Object[0];

    void init() {
        synchronized (lock) {
            // do init stuff
        }
    }

    public void close() {
        synchronized (lock) {
           // do close stuff
        }
    }
}

Expected outcome: Class passes PMD checks

PMD reports a violation at line 2 ..., but that's wrong. That's a false positive.

Running PMD through: [Maven]