code: public static final void assertProcessInActivity(final String processInstanceId, final String activityId) {
          Validate.notNull(processInstanceId);
          Validate.notNull(activityId);
  
          apiCallback.debug(LogMessage.PROCESS_15, processInstanceId, activityId);
          try {
              getProcessInstanceAssertable().processIsInActivity(processInstanceId, activityId);
          } catch (final AssertionError ae) {
              apiCallback.fail(ae, LogMessage.ERROR_PROCESS_6, processInstanceId, activityId);
          }
      }
docs: Asserts the process instance with the provided id is active and in (at lease) an activity with the provided id.
  
  @param processInstanceId
  the process instance's id to check for. May not be <code>null</code>
  @param activityId
  the activity's id to check for. May not be <code>null</code>