code: public static void ensure(boolean condition, String msg, Object... values) {
      getProvider().ensurePolicy().check(booleanContract(condition, describing(msg, values)));
    }
docs: Postcondition that supplier are supposed to ensure.
  Violations are considered to be programming errors,
  on the suppliers part.
  
  @param condition the condition to check
  @param msg       message {@link java.lang.String#format format string}
  @param values    values passed into the msg format string