Java method for examining IntelliJ PsiClass object for Constant Integer Fields

CallbackUtil.java

/**
 * @author Nicholas Nelson <nelsonni@oregonstate.edu> Created on on 7/28/16.
 */
public class CallbackUtil {
// ...

   /**
    * Examines all PsiFields within a target PsiClass and returns an array of Integer-type fields ordered by
    * their numerical values.
    *
    * @param psiClass       the class to target for analysis of all declared PsiFields.
    * @return an Optional containing constant Integer PsiFields ordered by Integer value; or Optional.empty if none.
    */
   @NotNull
   private static Optional<PsiField[]> getConstantIntegerFields(PsiClass psiClass) {
      PsiField[] fields = psiClass.getFields();
      PsiField[] integerFields = Arrays.stream(fields)
            .filter(f -> f.getType().equalsToText("int"))
            .filter(f -> f.computeConstantValue() != null)
            .sorted((f1, f2) -> Integer.compare((int) f1.computeConstantValue(), (int) f2.computeConstantValue()))
            .toArray(PsiField[]::new);
      return integerFields.length > 0 ? Optional.of(integerFields) : Optional.empty();
   } 
}