Exception in thread "main" org.tensorflow.exceptions.TensorFlowException: No gradient defined for op: SelectV2.

env :
tensorflow-java : 0.5.0-SNAPSHOT
scala :2.12.11
java : jdk 15
Hi :
when I defined a tf Variable named embeddings ,and want to do some operation with it, invoke the callone method

def clipByNormTF[T <: TNumber](someNums: Operand[T], clipNormBias: Operand[T], axis: Operand[TInt32], tf: Ops): Output[TFloat32] = {
    try {

      val l2sum = tf.reduceSum(tf.math.square(tf.dtypes.cast(someNums, classOf[TFloat64])), axis, ReduceSum.keepDims(true))
      val pred = tf.math.greater(l2sum, tf.constant(0.0))
      println("Here will crash !!! please ")
      val l2sumSafe = tf.select(pred, l2sum, tf.onesLike(l2sum))
      val l2norm = tf.select(pred, tf.math.sqrt(l2sumSafe), l2sum)

      val intermediate = tf.math.mul(tf.dtypes.cast(someNums, classOf[TFloat64]), tf.dtypes.cast(clipNormBias, classOf[TFloat64]))
      val valuesClip = tf.identity(tf.math.divNoNan(intermediate, tf.math.maximum(l2norm, tf.dtypes.cast(clipNormBias, classOf[TFloat64]))))
      if (someNums.shape().isCompatibleWith(intermediate.shape())) {
        println(s"match the shape ${someNums.shape().get(0)} ${someNums.shape().get(1)}  || ${intermediate.shape().get(0)} ${intermediate.shape().get(1)}")

        tf.dtypes.cast(valuesClip, classOf[TFloat32]).asOutput()
      } else {
        println(s"can not match the shape ${someNums.shape().get(0)} ${someNums.shape().get(1)}  || ${intermediate.shape().get(0)} ${intermediate.shape().get(1)}")
        throw new Exception("bad shape")
      }
    }

  def callOne(tf: Ops, input: Operand[T]): Operand[TFloat32] = {
    println(s"Embedding Layer ${this.layerName} input compute shape ${input.shape().asArray().mkString("|")}")
    val inputZ = tf.dtypes.cast(input, classOf[TInt32])
    val gatherResult = tf.gather(this.embeddings, inputZ, tf.constant(0))
    val gr = tf.dtypes.cast(gatherResult, classOf[TFloat32])
    val result = clipByNormTF(gr, tf.constant(this.maxNormBias), tf.constant(Array(1, 0)), tf)
    println(s"Embedding Layer call result shape  ${this.layerName}  compute output shape ${result.shape().asArray().mkString("|")}")
    result
  }

meet to error console

Exception in thread "main" org.tensorflow.exceptions.TensorFlowException: No gradient defined for op: SelectV2. Please see https://www.tensorflow.org/code/tensorflow/cc/gradients/README.md for instructions on how to add C++ gradients.
	at org.tensorflow.internal.c_api.AbstractTF_Status.throwExceptionIfNotOK(AbstractTF_Status.java:101)
	at org.tensorflow.Graph.addGradients(Graph.java:1152)
	at org.tensorflow.Graph.addGradients(Graph.java:703)
	at org.tensorflow.op.core.Gradients.create(Gradients.java:104)
	at org.tensorflow.op.core.Gradients.create(Gradients.java:125)
	at org.tensorflow.op.Ops.gradients(Ops.java:2814)

I do not know why , feel appreciate help me ,thanks

Commencez par le code fourni de clipByNormTF et callOne ainsi que par la trace de la pile passant par Graph.addGradients, Gradients.create et Ops.gradients. Reproduisez l’échec de SelectV2 avec tensorflow-java 0.5.0-SNAPSHOT, Scala 2.12.11 et JDK 15 ; le travail est terminé lorsque le comportement du gradient ou un correctif approprié est vérifié.