SolveFailedException for serializing objects in code-monkey

We modified the test case `testTrivialPojo` in `code-monkey` by changing the constructor of TrivialPojo to:
```
public TrivialPojo(String a, String b) {
this.firstName = a + "AA";
this.lastName = b;
}
```
This triggers `SolveFailedException` when serializing the code. Is this due to limitation of the approach?

Start with the code-monkey test case testTrivialPojo and reproduce serialization after changing TrivialPojo's constructor as shown. Trace where SolveFailedException is raised and compare this behavior with the project's serialization approach. Done means determining whether the failure is an expected limitation or an implementation bug, with the relevant behavior documented or corrected.

Written by the indexing model from the issue text.