code: public Set<Object> getAllSources() {
  		Set<Object> allSources = new LinkedHashSet<>();
  		if (!CollectionUtils.isEmpty(this.primarySources)) {
  			allSources.addAll(this.primarySources);
  		}
  		if (!CollectionUtils.isEmpty(this.sources)) {
  			allSources.addAll(this.sources);
  		}
  		return Collections.unmodifiableSet(allSources);
  	}
docs: Return an immutable set of all the sources that will be added to an
  ApplicationContext when {@link #run(String...)} is called. This method combines any
  primary sources specified in the constructor with any additional ones that have
  been {@link #setSources(Set) explicitly set}.
  @return an immutable set of all sources