@Inject(optional = true) private void register(Set<ResolvingProjectStateHolder> holders) { for (ResolvingProjectStateHolder holder : holders) { final String projectType = holder.getProjectType(); if (this.resolvingProjectStateHolders.containsKey(projectType)) { Log.warn( this.getClass(), "Resolving project state holder for '" + projectType + "' project type is already registered."); } else { this.resolvingProjectStateHolders.put(projectType, holder); } } }