The descriptive name for operator used for the filter, can be one of the following:

• equals
• not equals
• begins with
• not begins with
• contains
• not contains
• greater than
• greater than or equal
• less than
• less than or equal
• between
• not between
• is one of
• is not one of
• is known
• is unknown
• is yes
• is no

public string Operator { get; set; }