code: public void setGroups(java.util.Collection<Group> groups) {
          if (groups == null) {
              this.groups = null;
              return;
          }
  
          this.groups = new java.util.ArrayList<Group>(groups);
      }
docs: <p>
  The groups that this time period includes.
  </p>
  
  @param groups
  The groups that this time period includes.