The test class `KeywordFieldMapperTests` contains a switch statement with a branch that will never execute. The test uses a `between(x, y)` switch expression, but the `4` case is outside the randomised range. We need to fix this before #88739 can be merged. By "fix", I mean either remove the spurious case, or if we actually want it then extend the randomized range.
server/src/test/java/org/elasticsearch/index/mapper/KeywordFieldMapperTests.java
/**
     * Creates a copy of the lowercase token filter which we use for testing merge errors.
     */
    public static class MockAnalysisPlugin extends Plugin implements AnalysisPlugin {
        @Override
        public List<PreConfiguredTokenFilter> getPreConfiguredTokenFilters() {
            return singletonList(PreConfiguredTokenFilter.singleton("mock_other_lowercase", true, MockLowerCaseFilter::new));
        }
        @Override
        public Map<String, AnalysisModule.AnalysisProvider<TokenizerFactory>> getTokenizers() {
            return singletonMap(
                "keyword",
                (indexSettings, environment, name, settings) -> TokenizerFactory.newFactory(
                    name,
                    () -> new MockTokenizer(MockTokenizer.KEYWORD, false)
                )
            );
        }
    }
    @Override
    protected Object getSampleValueForDocument() {
        return "value";
    }