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/DynamicFieldsBuilder.java
void newDynamicStringField(DocumentParserContext context, String name) throws IOException;
        void newDynamicLongField(DocumentParserContext context, String name) throws IOException;
        void newDynamicDoubleField(DocumentParserContext context, String name) throws IOException;
        void newDynamicBooleanField(DocumentParserContext context, String name) throws IOException;
        void newDynamicDateField(DocumentParserContext context, String name, DateFormatter dateFormatter) throws IOException;
    }
    /**
     * Dynamically creates concrete fields, as part of the properties section.
     * Use for leaf fields, when their parent object is mapped as dynamic:true
     * @see Dynamic
     */
    private static final class Concrete implements Strategy {