Rule Definition
Utility classes are not meant to be instantiated because all the functionalities that they provide are accessible without instantiating the class. Instantiating these classes means that the developer has effectively misued the class. It also consumes memory unnecessarily. Providing a private default constructor ensures that the class is not instantiated.

Remediation
Add a private default constructor to ensure that the class can't be instantiated.

Violation Code Sample

public class MyUtilityClass
   {
      static public bool MyUtilityFunction1() {
            //Do Something Usefull 
            return true;
      }
   } }  // VIOLATION

Fixed Code Sample

public class MyUtilityClass
   {
      static public bool MyUtilityFunction1() {
            //Do Something Usefull 
            return true;
      }
      private MyUtilityClass() {   // FIXED
            // Avoid instantiation of the class
      }
   }