How do these two functions work?

Could someone show me how this code works or add some comments to it?
public String populateTreeAsXML() throws ManagementSupportException {
            StringBuffer buffer = new StringBuffer();
            long[] projectIds = this.getProjects();
            for(long id : projectIds) {
                  buffer.append(this.populateTreeAsXML(id)).append("\n");
            }
            return buffer.toString();
      }

      public String populateTreeAsXML(long nodeId) throws ManagementSupportException {
            TEServiceStub.GetProjectTree request = new TEServiceStub.GetProjectTree();

            request.setNodeID(nodeId);

            TEServiceStub.GetProjectTreeResponse response = null;
            try {
                  response = stub.getProjectTree(request);
            } catch (RemoteException e) {
                  logger.warn("Fail to call TEService :" + e);
                  throw new ManagementSupportException("Fail to call TEService :" + e);
            }

            if(!response.getStatus().getSuccess()) {
                  logger.warn("TEService return failure while call saveTestLog()");
                  throw new ManagementSupportException("TEService return failure while call saveTestLog()");
            }

            return response.getOMElement(TEServiceStub.GetProjectTreeResponse.MY_QNAME, OMAbstractFactory.getOMFactory()).toString();
      }