unfiltered.put("three", 3);
    unfiltered.put("four", 4);
    assertEquals(ImmutableMap.of("two", 2, "three", 3, "four", 4), unfiltered);
    assertEquals(ImmutableMap.of("three", 3, "four", 4), filtered);

    unfiltered.remove("three");
    assertEquals(ImmutableMap.of("two", 2, "four", 4), unfiltered);
    assertEquals(ImmutableMap.of("four", 4), filtered);

    unfiltered.clear();

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          do not modify the License. You may add Your own attribution
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          do not modify the License. You may add Your own attribution
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          or as an addendum to the NOTICE text from the Work, provided
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          do not modify the License. You may add Your own attribution
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          do not modify the License. You may add Your own attribution
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          or as an addendum to the NOTICE text from the Work, provided
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          do not modify the License. You may add Your own attribution
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          do not modify the License. You may add Your own attribution
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      You may add Your own copyright statement to Your modifications and