filtered.put("a", 1);
    filtered.put("b", 2);
    assertEquals(ImmutableMap.of("a", 1, "b", 2), filtered);

    assertThrows(IllegalArgumentException.class, () -> filtered.put("yyy", 3));
  }

  public void testFilteredKeysIllegalPutAll() {
    Map<String, Integer> unfiltered = createUnfiltered();
    Map<String, Integer> filtered = Maps.filterKeys(unfiltered, NOT_LENGTH_3);
    filtered.put("a", 1);

    suite.addTest(testsForTransform());
    suite.addTestSuite(Collections2Test.class);
    return suite;
  }

  static final Predicate<@Nullable String> NOT_YYY_ZZZ =
      input -> !Objects.equals(input, "yyy") && !Objects.equals(input, "zzz");

  static final Predicate<String> LENGTH_1 = input -> input.length() == 1;

  @J2ktIncompatible
  @GwtIncompatible // suite
  @AndroidIncompatible // test-suite builders

        systemHelper.addDesignJspFileName("xxx", "yyy");
        assertEquals("yyy", systemHelper.getDesignJspFileName("xxx"));
        final Pair<String, String>[] designJspFileNames = systemHelper.getDesignJspFileNames();
        assertEquals(1, designJspFileNames.length);
        assertEquals("xxx", designJspFileNames[0].getFirst());
        assertEquals("yyy", designJspFileNames[0].getSecond());
    }

    filtered.put("a", 1);
    filtered.put("b", 2);
    assertEquals(ImmutableMap.of("a", 1, "b", 2), filtered);

    assertThrows(IllegalArgumentException.class, () -> filtered.put("yyy", 3));
  }

  public void testFilteredKeysIllegalPutAll() {
    Map<String, Integer> unfiltered = createUnfiltered();
    Map<String, Integer> filtered = Maps.filterKeys(unfiltered, NOT_LENGTH_3);
    filtered.put("a", 1);

            new TestStringSetGenerator() {
              @Override
              public Set<String> create(String[] elements) {
                Set<String> unfiltered = new LinkedHashSet<>();
                unfiltered.add("yyy");
                Collections.addAll(unfiltered, elements);
                unfiltered.add("zzz");
                return Sets.filter(unfiltered, Collections2Test.NOT_YYY_ZZZ);
              }
            })

arrow"),W("y",["y",1],"yo","eraYear"),W("y",["yy",2],0,"eraYear"),W("y",["yyy",3],0,"eraYear"),W("y",["yyyy",4],0,"eraYear"),le("N",_t),le("NN",_t),le("NNN",_t),le("NNNN",function(e,a){return a.erasNameRegex(e)}),le("NNNNN",function(e,a){return a.erasNarrowRegex(e)}),Le(["N","NN","NNN","NNNN","NNNNN"],function(e,a,t,s){var n=t._locale.erasParse(e,s,t._strict);n?L(t).era=n:L(t).invalidEra=e}),le("y",ie),le("yy",ie),le("yyy",ie),le("yyyy",ie),le("yo",function(e,a){return a._eraYearOrdinalRegex||ie...