code: static ClassInfo getOrCreateClassInfo(final String className, final int classModifiers,
              final Map<String, ClassInfo> classNameToClassInfo) {
          ClassInfo classInfo = classNameToClassInfo.get(className);
          if (classInfo == null) {
              classNameToClassInfo.put(className,
                      classInfo = new ClassInfo(className, classModifiers, /* classfileResource = */ null));
          }
          classInfo.setModifiers(classModifiers);
          return classInfo;
      }
docs: Get a ClassInfo object, or create it if it doesn't exist. N.B. not threadsafe, so ClassInfo objects should
  only ever be constructed by a single thread.
  
  @param className
  the class name
  @param classModifiers
  the class modifiers
  @param classNameToClassInfo
  the map from class name to class info
  @return the or create class info