ADDITIONAL SYSTEM INFORMATION :
OS: windows 11 and CentOS 7
Java 11.0.12

A DESCRIPTION OF THE PROBLEM :
When using following ternary conditional operator will throw NPE:

    public static void main(String[] args) {
        BigDecimal a = null;
        BigDecimal b = null;
        Double x = a!=null ?
                a.doubleValue() : (
                    b!=null ?
                    b.doubleValue() :
                    null
                );
        System.out.print(x);
    }

the byte generated byte code as following:
  public static void main(java.lang.String[]);
    Code:
       0: aconst_null
       1: astore_1
       2: aconst_null
       3: astore_2
       4: aload_1
       5: ifnull        15
       8: aload_1
       9: invokevirtual #2                  // Method java/math/BigDecimal.doubleValue:()D
      12: goto          33
      15: aload_2
      16: ifnull        29
      19: aload_2
      20: invokevirtual #2                  // Method java/math/BigDecimal.doubleValue:()D
      23: invokestatic  #3                  // Method java/lang/Double.valueOf:(D)Ljava/lang/Double;
      26: goto          30
      29: aconst_null
      30: invokevirtual #4                  // Method java/lang/Double.doubleValue:()D
      33: invokestatic  #3                  // Method java/lang/Double.valueOf:(D)Ljava/lang/Double;
      36: astore_3
      37: getstatic     #5                  // Field java/lang/System.out:Ljava/io/PrintStream;
      40: aload_3
      41: invokevirtual #6                  // Method java/io/PrintStream.print:(Ljava/lang/Object;)V
      44: return

as above, see label 30 and 34: hotspot optimize the second ternary conditional operator with type inference assume it was a Double and invoked boxing / unboxing that caused NPE.


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
    public static void main(String[] args) {
        BigDecimal a = null;
        BigDecimal b = null;
        Double x = a!=null ?
                a.doubleValue() : (
                    b!=null ?
                    b.doubleValue() :
                    null
                );
        System.out.print(x);
    }

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
print null
ACTUAL -
NullPointException raised

---------- BEGIN SOURCE ----------
    public static void main(String[] args) {
        BigDecimal a = null;
        BigDecimal b = null;
        Double x = a!=null ?
                a.doubleValue() : (
                    b!=null ?
                    b.doubleValue() :
                    null
                );
        System.out.print(x);
    }
---------- END SOURCE ----------

FREQUENCY : always