### Question:
ImmutableCharacterEncoding implements CharacterEncoding { @Override public boolean isWildcard() { return this.charset==null; } ImmutableCharacterEncoding(Charset charset); @Override boolean isWildcard(); @Override String name(); @Override Charset charset(); @Override String toHeader(); @Override int hashCode(); @Override boolean equals(Object obj); @Override String toString();  }### Answer:
@Test public void nullCharsetsAreUsedForWildcards() throws Exception { assertThat(wildcard().isWildcard(),equalTo(true)); }
@Test public void nonNullCharsetsAreUsedForRegularCharacteEncodings() throws Exception { assertThat(regular().isWildcard(),equalTo(false)); }