code: @Override
      public void makeBuildVariables(@SuppressWarnings("rawtypes") AbstractBuild build, Map<String, String> variables) {
          variables.put("ghprbShowMatrixStatus", Boolean.toString(getShowMatrixStatus()));
          variables.put("ghprbUpstreamStatus", "true");
          variables.put("ghprbCommitStatusContext", getCommitStatusContext());
          variables.put("ghprbTriggeredStatus", getTriggeredStatus());
          variables.put("ghprbStartedStatus", getStartedStatus());
          variables.put("ghprbStatusUrl", getStatusUrl());
          variables.put("ghprbAddTestResults", Boolean.toString(getAddTestResults()));
  
          Map<GHCommitState, StringBuilder> statusMessages = new HashMap<GHCommitState, StringBuilder>(INITIAL_CAPACITY);
  
          for (GhprbBuildResultMessage message : getCompletedStatus()) {
              GHCommitState state = message.getResult();
              StringBuilder sb;
              if (!statusMessages.containsKey(state)) {
                  sb = new StringBuilder();
                  statusMessages.put(state, sb);
              } else {
                  sb = statusMessages.get(state);
                  sb.append("\n");
              }
              sb.append(message.getMessage());
          }
  
          for (Entry<GHCommitState, StringBuilder> next : statusMessages.entrySet()) {
              String key = String.format("ghprb%sMessage", next.getKey().name());
              variables.put(key, next.getValue().toString());
          }
      }
docs: sets the context and message as env vars so that they are available in the Listener class