Program: 12707
Project: 12707
Buggy source:
/** 
 * This method is ONLY valid for compliant URIs. Create a copy of the given top-level object, which is i.e.  {@link Collection},   {@link ComponentDefinition},   {@link Model},   {@link ModuleDefinition},  {@link Sequence}, or   {@link GenericTopLevel} with the given URIprefix, display ID, and version. Then add it to its corresponding top-level objects list.
 * @return the copied {@link TopLevel} object
 */
public TopLevel createCopy(TopLevel toplevel,String URIprefix,String displayId,String version){
  checkReadOnly();
  if (URIprefix == null) {
    URIprefix=extractURIprefix(toplevel.getIdentity());
  }
  if (displayId == null) {
    displayId=extractDisplayId(toplevel.getIdentity());
  }
  if (version == null) {
    version=extractVersion(toplevel.getIdentity());
  }
  if (toplevel instanceof Collection) {
    Collection newCollection=((Collection)toplevel).copy(URIprefix,displayId,version);
    addCollection(newCollection);
    return newCollection;
  }
 else   if (toplevel instanceof ComponentDefinition) {
    ComponentDefinition newComponentDefinition=((ComponentDefinition)toplevel).copy(URIprefix,displayId,version);
    addComponentDefinition(newComponentDefinition);
    return newComponentDefinition;
  }
 else   if (toplevel instanceof Model) {
    Model newModel=((Model)toplevel).copy(URIprefix,displayId,version);
    addModel(newModel);
    return newModel;
  }
 else   if (toplevel instanceof ModuleDefinition) {
    ModuleDefinition newModuleDefinition=((ModuleDefinition)toplevel).copy(URIprefix,displayId,version);
    addModuleDefinition(newModuleDefinition);
    return newModuleDefinition;
  }
 else   if (toplevel instanceof Sequence) {
    Sequence newSequence=((Sequence)toplevel).copy(URIprefix,displayId,version);
    addSequence(newSequence);
    return newSequence;
  }
 else   if (toplevel instanceof GenericTopLevel) {
    GenericTopLevel newGenericTopLevel=((GenericTopLevel)toplevel).copy(URIprefix,displayId,version);
    addGenericTopLevel(newGenericTopLevel);
    return newGenericTopLevel;
  }
 else {
    throw new IllegalArgumentException("String_Node_Str" + toplevel.getIdentity());
  }
}

Fixed version (ground truth):
/** 
 * This method is ONLY valid for compliant URIs. Create a copy of the given top-level object, which is i.e.  {@link Collection},   {@link ComponentDefinition},   {@link Model},   {@link ModuleDefinition},  {@link Sequence}, or   {@link GenericTopLevel} with the given URIprefix, display ID, and version. Then add it to its corresponding top-level objects list.
 * @return the copied {@link TopLevel} object
 */
public TopLevel createCopy(TopLevel topLevel,String URIprefix,String displayId,String version){
  checkReadOnly();
  if (URIprefix == null) {
    URIprefix=extractURIprefix(topLevel.getIdentity());
    URIprefix=checkURIprefix(URIprefix);
  }
 else {
    URIprefix=checkURIprefix(URIprefix);
  }
  if (displayId == null) {
    displayId=topLevel.getDisplayId();
  }
  if (version == null) {
    version=topLevel.getVersion();
  }
  validateIdentityData(displayId,version);
  if (topLevel instanceof Collection) {
    Collection newCollection=((Collection)topLevel).copy(URIprefix,displayId,version);
    addCollection(newCollection);
    return newCollection;
  }
 else   if (topLevel instanceof ComponentDefinition) {
    ComponentDefinition newComponentDefinition=((ComponentDefinition)topLevel).copy(URIprefix,displayId,version);
    addComponentDefinition(newComponentDefinition);
    return newComponentDefinition;
  }
 else   if (topLevel instanceof Model) {
    Model newModel=((Model)topLevel).copy(URIprefix,displayId,version);
    addModel(newModel);
    return newModel;
  }
 else   if (topLevel instanceof ModuleDefinition) {
    ModuleDefinition newModuleDefinition=((ModuleDefinition)topLevel).copy(URIprefix,displayId,version);
    addModuleDefinition(newModuleDefinition);
    return newModuleDefinition;
  }
 else   if (topLevel instanceof Sequence) {
    Sequence newSequence=((Sequence)topLevel).copy(URIprefix,displayId,version);
    addSequence(newSequence);
    return newSequence;
  }
 else   if (topLevel instanceof GenericTopLevel) {
    GenericTopLevel newGenericTopLevel=((GenericTopLevel)topLevel).copy(URIprefix,displayId,version);
    addGenericTopLevel(newGenericTopLevel);
    return newGenericTopLevel;
  }
 else {
    throw new IllegalArgumentException("String_Node_Str" + topLevel.getIdentity());
  }
}