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
Map.entry("other_lowercase", new NamedAnalyzer("other_lowercase", AnalyzerScope.INDEX, new LowercaseNormalizer())),
                Map.entry("default", new NamedAnalyzer("default", AnalyzerScope.INDEX, new LowercaseNormalizer()))
            ),
            Map.of(
                "lowercase",
                new NamedAnalyzer(
                    "lowercase",
                    AnalyzerScope.INDEX,
                    new CustomAnalyzer(
                        TokenizerFactory.newFactory("lowercase", WhitespaceTokenizer::new),
                        new CharFilterFactory[0],
                        new TokenFilterFactory[] { new TokenFilterFactory() {
                            @Override
                            public String name() {
                                return "lowercase";
                            }
                            @Override
                            public TokenStream create(TokenStream tokenStream) {
                                return new LowerCaseFilter(tokenStream);
                            }
                        } }
                    )
                )
            )
        );
    }
    @Override
    protected void minimalMapping(XContentBuilder b) throws IOException {
        b.field("type", "keyword");
    }