Map<String, String> changes = new HashMap<String, String>(nsp.getNamespaces());
NamespaceRegistry nsReg = getRepositorySession().getWorkspace().getNamespaceRegistry();
for (String prefix : nsReg.getPrefixes()) {
if (!changes.containsKey(prefix)) {
// prefix not present amongst the new values any more > unregister
nsReg.unregisterNamespace(prefix);
} else if (changes.get(prefix).equals(nsReg.getURI(prefix))) {
// present with same uri-value >> no action required
changes.remove(prefix);
}
}