code: public static DeserializerStringCache from(DeserializationContext context) {
          return withCache(context, cache -> {
              if (cache == null) {
                  cache = new DeserializerStringCache(new HashMap<CharBuffer, String>(),
                          new HashMap<CharBuffer, String>());
              }
              return cache;
          });
      }
docs: extracts a DeserializerStringCache from the DeserializationContext
  
  @param context
  an existing DeserializationContext containing a
  DeserializerStringCache
  @return a wrapped ObjectReader with the string cache attribute