ClassInfo getSuperclass() {
      if (superClass == null) {
        return null;
      }
      return new ClassInfo(superClass, loader, alwaysStatic);
    }
For a given class, this stores the information needed by the
getCommonSuperClass test.  This determines if the class is
available at runtime, and then, if it isn't, it tries to get the
class file, and extract the appropriate information from that.
src/main/java/com/google/monitoring/runtime/instrumentation/StaticClassWriter.java