code: public static Optional<Field> resolveField(Class<?> someClass, String fieldName) {
          return fieldCache.get(new FieldReference(someClass, fieldName));
      }
docs: Returns the specified field found on the specified class and its ancestors.
  
  @param someClass the class to search the field on.
  @param fieldName the field name.
  @return the corresponding field object wrapped in an optional.