private void parseBitmap(String attribute, String value, String bitmap) {
        if (bitmap.charAt(0) == '[') {
            parseBitmapList(attribute, value, bitmap);
        } else {
            parseBitmapHex(attribute, value, bitmap);
        }
    }
Handles one attribute, possibly with a subquery bitmap.
@param attribute Attribute name
@param value Either value, or value:bitmap, where bitmap is either a 64-bit hex number or a list of bits.
container-search/src/main/java/com/yahoo/search/querytransform/BooleanAttributeParser.java