/**
  * Identify a set of modifications in a a chains.
  *
  * @param chain query {@link Chain}.
  * @param potentialModifications query {@link ProteinModification}s.
  */
 public void identify(final Chain chain, final Set<ProteinModification> potentialModifications) {
   identify(Collections.singletonList(chain), potentialModifications);
 }
 /**
  * Identify all registered modifications in a chain.
  *
  * @param chain query {@link Chain}.
  */
 public void identify(final Chain chain) {
   identify(Collections.singletonList(chain));
 }