code: static ObjectStreamClass lookupStreamClass(Class<?> cl) {
          WeakHashMap<Class<?>, ObjectStreamClass> tlc = getCache();
          ObjectStreamClass cachedValue = tlc.get(cl);
          if (cachedValue == null) {
              cachedValue = createClassDesc(cl);
              tlc.put(cl, cachedValue);
          }
          return cachedValue;
  
      }
docs: Return the descriptor (ObjectStreamClass) corresponding to the class
  {@code cl}. Returns an ObjectStreamClass even if instances of the
  class cannot be serialized
  
  @param cl
  a java.langClass for which to obtain the corresponding
  descriptor
  @return the corresponding descriptor