来自 C 的 Dart FFI 结构

问：

typedef struct _TEST_NAME {
// variables

union
    {
        UCHAR FlagGroup[4];
        ULONG Flags;

        struct
        {
            ULONG PackagedBinary            : 1;
            ULONG MarkedForRemoval          : 1;
            ULONG ImageDll                  : 1;
            ULONG LoadNotificationsSent     : 1;
            ULONG TelemetryEntryProcessed   : 1;
            ULONG ProcessStaticImport       : 1;
            ULONG InLegacyLists             : 1;
            ULONG InIndexes                 : 1;
            ULONG ShimDll                   : 1;
            ULONG InExceptionTable          : 1;
            ULONG ReservedFlags1            : 2;
            ULONG LoadInProgress            : 1;
            ULONG ReservedFlags2            : 1; 
            ULONG EntryProcessed            : 1;
            ULONG ReservedFlags3            : 3;
            ULONG DontCallForThreads        : 1;
            ULONG ProcessAttachCalled       : 1;
            ULONG ProcessAttachFailed       : 1;
            ULONG CorDeferredValidate       : 1;
            ULONG CorImage                  : 1;
            ULONG DontRelocate              : 1;
            ULONG CorILOnly                 : 1;
            ULONG ReservedFlags5            : 3;
            ULONG Redirected                : 1;
            ULONG ReservedFlags6            : 2;
            ULONG CompatDatabaseProcessed   : 1;
        };
    };

// variables
} TEST_NAME, PTEST_NAME*;

sealed class TEST_NAME extends Struct {
  // variables
  external _union1 union;
  // variables
}

sealed  class _union1 extends Union {
 @Array(4)
 external Array<Uint8> FlagGroup;
 @Uint32()
 external int Flags;
 external _nestedStruct1 nestedStruct;
}

sealed class _nestedStruct1 extends Struct {
 // What here? Like this? How do i specify this ": 1"? If i do something like
 // "= 1", it shows an error. Do i even need to specify this values?
  @Uint32()
  external int packagedBinary;
  @Uint32()
  external int markedForRemoval;
  @Uint32()
  external int imageDll;
  @Uint32()
  external int loadNotificationsSent;
  @Uint32()
  external int telemetryEntryProcessed;
  @Uint32()
  external int processStaticImport;
  @Uint32()
  external int inLegacyLists;
  @Uint32()
  external int inIndexes;
  @Uint32()
  external int shimDll;
  @Uint32()
  external int inExceptionTable;
  @Uint32()
  external int reservedFlags1;
  @Uint32()
  external int loadInProgress;
  @Uint32()
  external int reservedFlags2;
  @Uint32()
  external int entryProcessed;
  @Uint32()
  external int reservedFlags3;
  @Uint32()
  external int dontCallForThreads;
  @Uint32()
  external int processAttachCalled;
  @Uint32()
  external int processAttachFailed;
  @Uint32()
  external int corDeferredValidate;
  @Uint32()
  external int corImage;
  @Uint32()
  external int dontRelocate;
  @Uint32()
  external int corILOnly;
  @Uint32()
  external int reservedFlags5;
  @Uint32()
  external int redirected;
  @Uint32()
  external int reservedFlags6;
  @Uint32()
  external int compatDatabaseProcessed;
}

如何将这个嵌套的 Struct 适当地转换为 dart？