Bonjour,

j'essaye de mapper des list de String en utulisant mapstruct et lorsque je n'ai qu'une liste il y'a pas d'erreur mais dès lors que j'ai plus d'une liste de même type, l'erreur 

 UnsupportedOperation

est générée. voici ma class mapper 

@Mapper(
    collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED,
    nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS,
    uses = ProtoWrappersMapper.class)
public interface MemberImportResultMapper {
  MemberImportResultMapper INSTANCE = Mappers.getMapper(MemberImportResultMapper.class);

  @Mapping(source = "rejected", target = "rejectedList")
  @Mapping(source = "accepted", target = "acceptedList")
  MemberImportResultDto fromMemberImportResult(MemberImportResult memberImportResult);
}

mon test 

public class MemberImportResultMapperTest {

  private MemberImportResultMapper mapper = Mappers.getMapper(MemberImportResultMapper.class);

  @Test
  public void whenFromMemberImportResult_givenMemberImportResult_thenMemberImportResultDto() {

    MemberImportResult memberImportResult =
        MemberImportResult.builder()
            .nbProcessedLines(3)
            .rejected(Collections.singletonList("yvan@gmail.com"))
            .accepted(Arrays.asList("paul@gmail.com", "pierre@yahoo.fr"))
            .build();

    MemberImportResultDto memberImportResultDto = mapper.fromMemberImportResult(memberImportResult);

    assertEquals(
        memberImportResultDto.getNbProcessedLines().getValue(),
        memberImportResult.getNbProcessedLines());
    assertEquals(
        memberImportResultDto.getRejectedList().size(),
        memberImportResult.getRejected().size());

    assertEquals(
        memberImportResultDto.getAcceptedList().size(),
        memberImportResult.getAccepted().size());
  }
}

mes classes objet que j'ai bien évidement simplifié pour illustré le problème

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@FieldDefaults(level = AccessLevel.PRIVATE)
@JsonInclude(JsonInclude.Include.NON_NULL)
public class MemberImportResult {
  private long nbProcessedLines;

  @Builder.Default private List<String> rejected= new ArrayList<>();

  @Builder.Default private List<String> accepted = new ArrayList<>();
}

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@FieldDefaults(level = AccessLevel.PRIVATE)
@JsonInclude(JsonInclude.Include.NON_NULL)
public class MemberImportResultDto {
  private long nbProcessedLines;

  @Builder.Default private List<String> rejected= new ArrayList<>();

  @Builder.Default private List<String> accepted = new ArrayList<>();
}

Merci