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/main/java/org/elasticsearch/index/mapper/BooleanFieldMapper.java
}
        indexValue(context, value);
    }
    private void indexValue(DocumentParserContext context, Boolean value) {
        if (value == null) {
            return;
        }
        if (indexed) {
            context.doc().add(new Field(fieldType().name(), value ? "T" : "F", Defaults.FIELD_TYPE));
        }
        if (stored) {
            context.doc().add(new StoredField(fieldType().name(), value ? "T" : "F"));
        }
        if (hasDocValues) {
            context.doc().add(new SortedNumericDocValuesField(fieldType().name(), value ? 1 : 0));
        } else {
            context.addToFieldNames(fieldType().name());
        }
    }
    @Override
    protected void indexScriptValues(
        SearchLookup searchLookup,
        LeafReaderContext readerContext,
        int doc,
        DocumentParserContext documentParserContext
    ) {
        this.scriptValues.valuesForDoc(searchLookup, readerContext, doc, value -> indexValue(documentParserContext, value));
    }
    @Override
    public FieldMapper.Builder getMergeBuilder() {