Rule S2755 is raising FPs when having issue in classpath to resolve XML implementation classes

When having classpath issue (namely, multiple XML implementation provided), it's possible that the rule might not correctly detect method invocations supposed to sanitize the configuration, depending of the order in which the semantic encountered the XML API implementation classes.

Consequently, FPs might be raised, and, even worse, these FPs are usually exactly what the "Compliant" code is suggesting to do.

For instance, the following code can raise an issue, while perfectly valid, if method setFeature is not properly resolved by the semantic engine:

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
dbf.setFeature("http://apache.org/xml/features/disallow-doctype-decl",true);
dbf.setFeature("http://xml.org/sax/features/external-general-entities",false);
dbf.setFeature("http://xml.org/sax/features/external-parameter-entities",false);
dbf.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
dbf.setXIncludeAware(false);
bf.setExpandEntityReferences(false);

While fixing classpath issue in order to correctly know WHICH implementation of XML is used should fix the FP (see SONARJAVA-2957, SONARJAVA-3056). Another approach could be the following:

> Do not raise an issue if there is calls to unknown method called "setFeature" following the creation of the factory