IfMatchPreconditionHeader implements PreconditionHeader<EntityTag> { @Override public String getKey() { return IF_MATCH_HEADER_KEY; } private  IfMatchPreconditionHeader(final EntityTagMatchers entityTagsToMatch); @Override String getKey(); @Override String getValue(); @Override boolean meetsConditionFor(@Nullable final EntityTag entityTag); static Optional<IfMatchPreconditionHeader> fromDittoHeaders(final DittoHeaders dittoHeaders);  }
@Test public void getKey() { final IfMatchPreconditionHeader ifMatchPreconditionHeader = createIfMatchPreconditionHeader(fromCommaSeparatedString("\"test\"")); assertThat(ifMatchPreconditionHeader.getKey()).isEqualTo("if-match"); }