code: @SuppressWarnings({"ConstantConditions","deprecation"})
      @SuppressFBWarnings("RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE")
      public void addAction(@Nonnull Action a) {
          if(a==null) {
              throw new IllegalArgumentException("Action must be non-null");
          }
          getActions().add(a);
      }
docs: Adds a new action.
  Note: calls to {@link #getAllActions()} that happen before calls to this method may not see the update.
  <strong>Note: this method will always modify the actions</strong>