Import `BaseSettings` from Pydantic and create a sub-class, very much like with a Pydantic model.

The same way as with Pydantic models, you declare class attributes with type annotations, and possibly default values.

You can use all the same validation features and tools you use for Pydantic models, like different data types and additional validations with `Field()`.

//// tab | Pydantic v2

        void testConstructor_CIFSContext() {
            // Given
            CIFSContext mockContext = createMockContext();

            // When
            Type2Message message = new Type2Message(mockContext);

            // Then
            assertNotNull(message, "Message should not be null");
            // Verify default flags are set
            int expectedFlags =

		case replication.Pending, replication.Completed, replication.Failed, replication.Replica: // for backward compatibility
			return replication.StatusType(rs.ReplicationStatusInternal)
		default:
			replStatus := getCompositeReplicationStatus(rs.Targets)
			// return REPLICA status if replica received timestamp is later than replication timestamp
			// provided object replication completed for all targets.

public class FileFsSizeInformation implements AllocInfo {

    private long alloc; // Also handles SmbQueryFSSizeInfo
    private long free;
    private int sectPerAlloc;
    private int bytesPerSect;

    /**
     * Default constructor for decoding file system size information.
     */
    public FileFsSizeInformation() {
    }

    /**
     * {@inheritDoc}
     *

 * Contains the result of a witness heartbeat request.
 */
public class WitnessHeartbeatResponse {
    /**
     * Creates a new witness heartbeat response.
     */
    public WitnessHeartbeatResponse() {
        // Default constructor
    }

    private long sequenceNumber;
    private int returnCode;
    private long recommendedHeartbeatInterval;
    private String error;

    /**
     * Checks if the heartbeat was successful.

 * Contains the result of a witness registration request.
 */
public class WitnessRegisterResponse {
    /**
     * Creates a new witness register response.
     */
    public WitnessRegisterResponse() {
        // Default constructor
    }

    private String registrationId;
    private int returnCode;
    private byte[] contextHandle;
    private String error;

    /**
     * Checks if the registration was successful.

		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrInvalidCopyPartRange), url)
		return
	case errInvalidRangeSource:
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrInvalidCopyPartRangeSource), url)
		return
	default:
		apiErr := errorCodes.ToAPIErr(ErrInvalidCopyPartRangeSource)
		apiErr.Description = err.Error()
		writeErrorResponse(ctx, w, apiErr, url)
		return
	}
}

		kmsRouter.Methods(http.MethodGet).Path(version + "/key/status").HandlerFunc(gz(httpTraceAll(kmsAPI.KMSKeyStatusHandler)))
	}

	// If none of the routes match add default error handler routes
	kmsRouter.NotFoundHandler = httpTraceAll(errorResponseHandler)
	kmsRouter.MethodNotAllowedHandler = httpTraceAll(methodNotAllowedHandler("KMS"))

Because all the **fields actually change** (the type now includes `None` and they now have a default value of `None`), we need to **re-declare** them.

        assertEquals("WORKGROUP", defaultDomain, "Should delegate default domain");
        assertEquals("testuser", defaultUsername, "Should delegate default username");
        assertEquals("testpass", defaultPassword, "Should delegate default password");
        assertEquals("jCIFS", nativeLanMan, "Should delegate native LanMan");

        verify(mockDelegate).getOemEncoding();