[JVM] Change default missing value to NaN for better alignment (dmlc#11225)

Co-authored-by: a.cherkaoui <[email protected]>

Author: ayoub317

jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/DMatrix.java

@@ -136,7 +136,7 @@ public DMatrix(long[] headers, int[] indices, float[] data, DMatrix.SparseType s
   @Deprecated
   public DMatrix(float[] data, int nrow, int ncol) throws XGBoostError {
     long[] out = new long[1];
-    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixCreateFromMat(data, nrow, ncol, 0.0f, out));
+    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixCreateFromMat(data, nrow, ncol, Float.NaN, out));
     handle = out[0];
   }
 
@@ -147,7 +147,7 @@ public DMatrix(float[] data, int nrow, int ncol) throws XGBoostError {
    * @throws XGBoostError native error
    */
   public DMatrix(BigDenseMatrix matrix) throws XGBoostError {
-    this(matrix, 0.0f);
+    this(matrix, Float.NaN);
   }
 
   /**