The `ignore_malformed` option is supported by a few of our field types, mainly numerics and dates, to still accept the document when such fields hold malformed values. See https://www.elastic.co/guide/en/elasticsearch/reference/current/ignore-malformed.html. Also `ignore_malformed` is an index level setting that gets applied to all field types that support it. 

The boolean field type does not support `ignore_malformed` but it should, so that if a boolean field cannot be parsed as a boolean, the document can still be accepted.


server/src/test/java/org/elasticsearch/index/mapper/BooleanFieldMapperTests.java
b.endObject();
        })));
        assertEquals(
            "failed to parse field [field] of type [boolean] in document with id '1'. " + "Preview of field's value: '{inner_field=no}'",
            ex.getMessage()
        );
    }
    public void testMultiFields() throws IOException {
        DocumentMapper mapper = createDocumentMapper(fieldMapping(b -> {
            b.field("type", "boolean");
            b.startObject("fields");
            {
                b.startObject("as_string").field("type", "keyword").endObject();
            }
            b.endObject();
        }));
        ParsedDocument doc = mapper.parse(source(b -> b.field("field", false)));
        assertNotNull(doc.rootDoc().getField("field.as_string"));
    }
    public void testDocValues() throws Exception {
        DocumentMapper defaultMapper = createDocumentMapper(mapping(b -> {
            b.startObject("bool1").field("type", "boolean").endObject();
            b.startObject("bool2");
            {
                b.field("type", "boolean");
                b.field("index", false);
            }
            b.endObject();
            b.startObject("bool3");
            {