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
context,
                        name,
                        dateTimeFormatter,
                        () -> strategy.newDynamicDateField(context, name, dateTimeFormatter)
                    );
                    return;
                }
                createDynamicField(
                    context,
                    name,
                    DynamicTemplate.XContentFieldType.STRING,
                    () -> strategy.newDynamicStringField(context, name)
                );
            } else {
                createDynamicField(
                    context,
                    name,
                    DynamicTemplate.XContentFieldType.STRING,
                    () -> strategy.newDynamicStringField(context, name)
                );
            }
        } else if (token == XContentParser.Token.VALUE_NUMBER) {
            XContentParser.NumberType numberType = context.parser().numberType();
            if (numberType == XContentParser.NumberType.INT
                || numberType == XContentParser.NumberType.LONG
                || numberType == XContentParser.NumberType.BIG_INTEGER) {
                createDynamicField(
                    context,
                    name,
                    DynamicTemplate.XContentFieldType.LONG,