public static FieldUpdate createIncrement(Field field, Number increment) {
        return new FieldUpdate(field, ValueUpdate.createIncrement(increment));
    }
Creates a new field update, with one encapsulated value update that increments a value.
Note that the data type must be a numeric type.

@param field     the field to increment the value of
@param increment the number to increment by
@return a FieldUpdate specifying the increment
@throws UnsupportedOperationException if the data type is non-numeric
@see ValueUpdate#createIncrement(Number)
document/src/main/java/com/yahoo/document/update/FieldUpdate.java