docs: public static Object setAppThreadIdentity(Subject subject) throws ThreadIdentityException {
          LinkedHashMap<ThreadIdentityService, Object> token = null;
          for (ThreadIdentityService tis : threadIdentityServices) {
              if (tis.isAppThreadIdentityEnabled()) {
                  try {
                      Object tokenReturnedFromSet = tis.set(subject);
                      if (tokenReturnedFromSet != null) {
                          if (token == null) {
                              token = new LinkedHashMap<ThreadIdentityService, Object>();
                          }
                          token.put(tis, tokenReturnedFromSet);
                      }
                  } catch (Exception e) {
                      com.ibm.ws.ffdc.FFDCFilter.processException(e, thisClass, "251");
                      resetCheckedInternal(token, e);
                  }
              }
          }
          return token;
      }