@Override public Policy setSubjectsFor(final CharSequence label, final Subjects subjects) { final Label lbl = Label.of(label); checkNotNull(subjects, "subjects to set to the Policy entry"); final Map<Label, PolicyEntry> entriesCopy = copyEntries(); final PolicyEntry modifiedEntry; if (!entriesCopy.containsKey(lbl)) { modifiedEntry = newPolicyEntry(lbl, subjects, emptyResources()); } else { final PolicyEntry policyEntry = entriesCopy.get(lbl); modifiedEntry = newPolicyEntry(lbl, subjects, policyEntry.getResources()); } entriesCopy.put(lbl, modifiedEntry); return new ImmutablePolicy(policyId, entriesCopy, lifecycle, revision, modified); }