[GROOVY-8284] getMetaClass should be annotated as (JavaBeans) transient

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.12
• Fix Version/s: 4.0.0-alpha-1, 3.0.6
• Component/s: Compiler
• Assignee: Paul King
• Reporter: Michael Lipp
• Created: 10/Aug/17 11:35
• Updated: 11/Nov/20 02:01
• Resolved: 19/Sep/20 23:59

Description

All groovy classes have the "getMetaClass()" method. This breaks the (e.g. XML) serialization of groovy classes that are supposed to represent JavaBeans.

While the serialization provided with Serializable or Externalizable examines the attributes of a class, the special JavaBeans serialization provided by serializers based on [Encoders](https://docs.oracle.com/javase/8/docs/api/java/beans/Encoder.html) relies on the information provided by the [Introspector](https://docs.oracle.com/javase/8/docs/api/java/beans/Introspector.html).

With respect to persistence, the PropertyDescriptor for "getMetaClass" should have the attribute value "transient" set. The Introspector generates this value if the method has been annotated as [Transient](https://docs.oracle.com/javase/8/docs/api/java/beans/Transient.html)). Because this value is currently missing, the Encoder tries to serialize the MetaClass information, which fails.

The groovy compiler should therefore annotate the "getMetaClass" method with the runtime annotation "java.beans.Transient".