private void parseMultiValue(String attribute) {
        // string() will point to the start of value.
        string().consume('[');
        while (!string().peek(']')) {
            string().consumeSpaces();
            consumeValue(attribute);
            string().consumeOptional(',');
            string().consumeSpaces();
        }
    }
Parses a list of values for a given attribute. When calling this
function, string() must point to the start of the list.
container-search/src/main/java/com/yahoo/search/querytransform/BooleanAttributeParser.java