code: public void testQueryByKeys(){
    Set<String> one=new HashSet<String>();
    one.add("one");
    Set<String> two=new HashSet<String>();
    two.add("two");
    Set<String> oneAndTwo=new HashSet<String>();
    oneAndTwo.addAll(one);
    oneAndTwo.addAll(two);
    ProcessDefinitionQuery query=repositoryService.createProcessDefinitionQuery().processDefinitionKeys(one);
    verifyQueryResults(query,2);
    query=repositoryService.createProcessDefinitionQuery().processDefinitionKeys(two);
    verifyQueryResults(query,1);
    query=repositoryService.createProcessDefinitionQuery().processDefinitionKeys(oneAndTwo);
    verifyQueryResults(query,3);
  }
  