Search for JsonValue in all classes and interfaces

[T3rm1]

This PR fixes a regression introduced by issue #3998, which added support for @JsonValue on enum fields and private methods. That fix only searched getDeclaredMethods() on the enum class itself, breaking a valid Jackson pattern where @JsonValue is declared on an interface the enum implements.

---

What was broken

When an enum implements an interface that carries @JsonValue, swagger-core failed to find the annotation and fell back to raw enum constant names instead of the serialized values.

Case 1 — @JsonValue on an abstract interface method:

public interface InterfaceWithJacksonValue {
    @JsonValue
    int getJsonValue();
}

public enum JacksonValueInInterfaceEnum implements InterfaceWithJacksonValue {
    TEN(10);
    @Override public int getJsonValue() { return jsonValue; }
}
// Before: schema enum was ["TEN"]
// After:  schema enum is  [10]       ✓

Case 2 — @JsonValue on an interface default method (overridden without repeating the annotation):

public interface InterfaceWithDefaultJsonValue {
    @JsonValue
    default String toValue() { return "default"; }
}

public enum JacksonValueDefaultMethodEnum implements InterfaceWithDefaultJsonValue {
    ALPHA, BETA, GAMMA;
    @Override public String toValue() { return name().toLowerCase(); }
}
// Before: schema enum was ["ALPHA", "BETA", "GAMMA"]
// After:  schema enum is  ["alpha", "beta", "gamma"]  ✓

---

What changed

ModelResolver.java — The @JsonValue method lookup was changed from a one-class scan:

// Before
Arrays.stream(enumClass.getDeclaredMethods())
    .filter(m -> m.isAnnotationPresent(JsonValue.class))
    .filter(m -> m.getAnnotation(JsonValue.class).value())
    .findFirst();

to a full hierarchy scan using the new utility:

// After
ReflectionUtils.getAnnotatedMethods(enumClass, JsonValue.class).stream()
    .findFirst();

ReflectionUtils.java — New public method getAnnotatedMethods(Class<?> type, Class<? extends Annotation> annotation) that walks:

1. The class itself and all superclasses (up to but excluding Object)
2. All directly implemented interfaces, and their parent interfaces, recursively

The duplicate inner loop pattern was also refactored into a shared private helper collectAnnotatedDeclaredMethods.

---

@T3rm1 notes that the same gap exists for fields in inherited classes (not just methods), but intentionally defers that to a separate PR.

[MichakrawSB]

Thank you for your contribution! ❤️
We’re closing this PR as part of our ongoing cleanup of long-standing and inactive items.

Due to its age, we’re unable to review or merge it reliably.
If the change is still important, feel free to open a fresh PR and reference this one so we can evaluate it with full, updated context.

Thanks again for supporting the Swagger ecosystem!

[T3rm1]

What? Are you serious? This is an easy change. You didn't even try to merge it, did you?
It also has tests so it's simple to verify it's working.

[MichakrawSB]

Hi @T3rm1,

Sorry about this. We're doing a general cleanup to avoid very old PRs staying open for so long. I assumed this PR was no longer relevant since the linked issue was already closed.

If you're still waiting on this to be merged, I will reopen the PR.
A fresh issue with updated context would also help us review it faster.
Thanks!

[T3rm1]

This fixes a bug that was introduced by the issue that was closed. I think this is still relevant.

[T3rm1]

@MichakrawSB I rebased on master. Please add it to the backlog.

[ewaostrowska]

Thank you @T3rm1 for handling this regression. This is great! I have only added few more test cases and refactored the code slightly