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
}
    public void testConfigureSimilarity() throws IOException {
        MapperService mapperService = createMapperService(fieldMapping(b -> b.field("type", "keyword").field("similarity", "boolean")));
        MappedFieldType ft = mapperService.documentMapper().mappers().fieldTypesLookup().get("field");
        assertEquals("boolean", ft.getTextSearchInfo().similarity().name());
        IllegalArgumentException e = expectThrows(
            IllegalArgumentException.class,
            () -> merge(mapperService, fieldMapping(b -> b.field("type", "keyword").field("similarity", "BM25")))
        );
        assertThat(e.getMessage(), containsString("Cannot update parameter [similarity] from [boolean] to [BM25]"));
    }
    public void testNormalizer() throws IOException {
        DocumentMapper mapper = createDocumentMapper(fieldMapping(b -> b.field("type", "keyword").field("normalizer", "lowercase")));
        ParsedDocument doc = mapper.parse(source(b -> b.field("field", "AbC")));
        IndexableField[] fields = doc.rootDoc().getFields("field");
        assertEquals(2, fields.length);
        assertEquals(new BytesRef("abc"), fields[0].binaryValue());
        IndexableFieldType fieldType = fields[0].fieldType();
        assertThat(fieldType.omitNorms(), equalTo(true));
        assertFalse(fieldType.tokenized());
        assertFalse(fieldType.stored());
        assertThat(fieldType.indexOptions(), equalTo(IndexOptions.DOCS));
        assertThat(fieldType.storeTermVectors(), equalTo(false));
        assertThat(fieldType.storeTermVectorOffsets(), equalTo(false));
        assertThat(fieldType.storeTermVectorPositions(), equalTo(false));
        assertThat(fieldType.storeTermVectorPayloads(), equalTo(false));
        assertEquals(DocValuesType.NONE, fieldType.docValuesType());
        assertEquals(new BytesRef("abc"), fields[1].binaryValue());
        fieldType = fields[1].fieldType();
        assertThat(fieldType.indexOptions(), equalTo(IndexOptions.NONE));