public FieldValue createFieldValue(Object arg) {
        if (arg == null) {
            return createFieldValue();
        }
        FieldValue val = createByReflection(arg);
        if (val == null) {
            val = createFieldValue();
            if (val != null) {
                val.assign(arg);
            }
        }
        return val;
    }
Creates a new FieldValue of this type, with the given value.

@param arg the value of the new FieldValue
@return a new FieldValue of this type, with the given value
document/src/main/java/com/yahoo/document/DataType.java