src/main/java/de/digitalcollections/iiif/model/sharedcanvas/Range.java
public Range addMember(Resource first, Resource... rest) throws IllegalArgumentException {
    if (this.members == null) {
      this.members = new ArrayList<>();
    }
    List<Resource> membersToAdd = Lists.asList(first, rest);
    membersToAdd.forEach(this::checkMember);
    this.members.addAll(membersToAdd);
    return this;
  }
public Range addMember(Resource first, Resource... rest) throws IllegalArgumentException {
    if (this.members == null) {
      this.members = new ArrayList<>();
    }
    List<Resource> membersToAdd = Lists.asList(first, rest);
    membersToAdd.forEach(this::checkMember);
    this.members.addAll(membersToAdd);
    return this;
  }
Adds one or more member resources.
Must be either instances of {@link Range} or {@link Canvas}.
All members must have an identifier and a label.

@param first first member
@param rest other members
@return this instance with added members
@throws IllegalArgumentException if at least one member is not a {@link Range} or {@link Canvas} or does not have
an identifier and a label;