ClassLevelFieldMappingGenerator should ignore synthetic fields

[dimitarp]

• Dozer version: 6.5.0
• JDK version: 1.8.0_212

Steps to reproduce:

1. Mapping "declared fields accessible" classes
2. Run unit tests coverage with jacoco maven plugin

Observed Results:

ERROR c.g.d.core.MappingProcessor - Field mapping error -->
  MapId: null
  Type: null
  Source parent class: A
  Source field name: $jacocoData
  Source field type: class [Z
  Source field value: [Z@16be6b36
  Dest parent class: B
  Dest field name: $jacocoData
  Dest field type: [Z
java.lang.OutOfMemoryError: Java heap space

Expected Results:

Dozer should ignore the synthetic jacoco fields. From jacoco FAQ:

My code uses reflection. Why does it fail when I execute it with JaCoCo?
To collect execution data JaCoCo instruments the classes under test which adds two members to the classes: A private static field $jacocoData and a private static method $jacocoInit(). Both members are marked as synthetic.
Please change your code to ignore synthetic members. This is a good practice anyways as also the Java compiler creates synthetic members in certain situation.

[johannschenkl]

@garethahealy Has this been fixed or is this a not a dozer issue? We're currently seeing excessive memory (OOM) usage after upgrading to dozer 6.5.0 when jacoco is enabled. Thanks!

[garethahealy]

@johannschenkl ; no, I've not had time to investigate (and won't have any in the coming months). if you want to investigate/raise a PR, happy to review/merge.

[johannschenkl]

@garethahealy ok, perfect. it seems like just ignoring synthetic fields fixes the issues. I'll test a bit more and then try to raise a PR.