code: public Collection<Project> getChildProjects(ProjectFilter filter, boolean includeSubprojects) {
  
          if (filter == null) {
              filter = new ProjectFilter();
          }
          filter.parent.clear();
  
          if (includeSubprojects) {
              filter.parent.addAll(getThisAndAllChildProjects());
          } else {
              filter.parent.add(this);
          }
          return getInstance().get().projects(filter);
      }
docs: A collection of sub-projects that belong to this project.
  
  @param filter             Criteria to filter on. Project will be set automatically.
  If null, all child projects in the project are returned.
  @param includeSubprojects Specifies whether to include items from
  sub-project or not. This only adds open subprojects.
  @return A collection projects that belong to this project filtered by the
  passed in filter.