Some types are not found when invoking JavacInfo.getTypeMirror for type identifiers

[OscarRodriguezPrieto]

For some projects and some specific classes (some second classes in comp units), JavacInfo.getTypeMirror invocations throw
Caused by: java.lang.NullPointerException: Cannot invoke "com.sun.source.util.TreePath.getLeaf()" because "path" is null
when trying to add the type of (an array, isntanceof, cast...) to the dependency graph by invoking addClassIdentifier(JavacInfo.getTypeMirror(x.getType())

The solution is applying instanceof and cast to directly retrieve the type of the type identifier.