code: private String extractNamespace(Node call, String... primitiveNames) {
      Node callee = call.getFirstChild();
      if (!callee.isGetProp()) {
        return null;
      }
      for (String primitiveName : primitiveNames) {
        if (callee.matchesQualifiedName(primitiveName)) {
          Node target = callee.getNext();
          if (target != null && target.isString()) {
            return target.getString();
          }
        }
      }
      return null;
    }
docs: TODO(tbreisacher): Update CodingConvention.extractClassNameIf{Require,Provide} to match this.