Get parameters values of enum constructors in Java

I have enum which I cannot initialize during the testing (staticMethod() fails) and it is impossible for me to mock that call. Is there a way to get values of parameters passed to constructors via reflection (in this case I want to know that "Monday" and "Sunday" are passed)?

public enum Day {
    SATURDAY ("Monday"),
    SUNDAY   ("Sunday");

  private final String day;

  private Day(String day) {
    this.day = day;
    StaticClass.someMethod();
  }
}