code: private boolean isImplementationOf(@SlashedClassName String clsName, JavaClass inf) {
  
          try {
              if (clsName.startsWith("java/lang/")) {
                  return false;
              }
  
              JavaClass cls = Repository.lookupClass(clsName);
              return isImplementationOf(cls, inf);
          } catch (ClassNotFoundException cnfe) {
              bugReporter.reportMissingClass(cnfe);
          }
          return false;
      }
docs: returns whether the class implements the interface
  
  @param clsName
  the name of the class
  @param inf
  the interface to check
  @return if the class implements the interface