Enum value extraction from annotation no longer works correctly in Java 17+

[xcesco]

🐞 Issue: Enum value extraction from annotation no longer works correctly in Java 17+

Description

In our annotation processor, we previously used the following logic to extract the value of an enum attribute from an annotation:

if (value.indexOf(".") >= 0)
    result.value0 = value.substring(value.lastIndexOf(".") + 1);

This worked correctly under Java 8, where AnnotationValue.toString() returned the fully qualified name of the enum constant (e.g., com.example.XmlType.ATTRIBUTE). However, starting with Java 11 and confirmed in Java 17+, this behavior has changed.

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🔍 Analysis

• In Java 8:
  AnnotationValue.toString() returned the fully qualified name of the enum constant.
  Example:

  com.example.XmlType.ATTRIBUTE

• In Java 17+:
  AnnotationValue.toString() returns only the simple name of the constant:

  ATTRIBUTE

As a result, the old logic relying on the presence of "." to extract the enum name no longer works as expected.

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✅ Proposed Solution

Option 1: Backward-compatible parsing logic

String valueStr = value.toString();
if (valueStr.contains(".")) {
    result.value0 = valueStr.substring(valueStr.lastIndexOf(".") + 1);
} else {
    result.value0 = valueStr;
}

Option 2: More robust approach using VariableElement

Object actualValue = value.getValue();
if (actualValue instanceof VariableElement) {
    result.value0 = ((VariableElement) actualValue).getSimpleName().toString();
}

This second option avoids relying on the potentially fragile toString() output and instead leverages the standard annotation processing API.

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🧩 Notes

• This behavior change is not officially documented, so relying on toString() is inherently brittle.
• The VariableElement approach is recommended for long-term robustness and forward compatibility with future Java versions.