/**
   * Note: if you change this unit test, also change the cook book:
   * http://www.biojava.org/wiki/BioJava:CookBook3:SupportedProtMod
   */
  public void testGetBy() {
    ProteinModification mod;
    Set<ProteinModification> mods;

    mod = ProteinModificationRegistry.getById("0001");
    assertNotNull(mod);

    // a set of protein modifications by RESID ID
    mods = ProteinModificationRegistry.getByResidId("AA0151");
    assertNotNull(mods);

    // a set of protein modifications by PSI-MOD ID
    mods = ProteinModificationRegistry.getByPsimodId("MOD:00305");
    assertNotNull(mods);

    // a set of protein modifications by PDBCC ID
    mods = ProteinModificationRegistry.getByPdbccId("SEP");
    assertNotNull(mods);

    // a set of protein modifications by category
    mods = ProteinModificationRegistry.getByCategory(ModificationCategory.ATTACHMENT);
    assertNotNull(mods);

    // a set of protein modifications by occurrence type
    mods = ProteinModificationRegistry.getByOccurrenceType(ModificationOccurrenceType.NATURAL);
    assertNotNull(mods);

    // a set of protein modifications by a keyword
    mods = ProteinModificationRegistry.getByKeyword("phosphoprotein");
    assertNotNull(mods);

    // a set of protein modifications by involved components.
    mods = ProteinModificationRegistry.getByComponent(Component.of("FAD"));
    assertNotNull(mods);
  }