add functionality to multiply Quantity by a scalar value

Author: bachmanity1

kubernetes-model-generator/kubernetes-model-core/src/main/java/io/fabric8/kubernetes/api/model/Quantity.java

@@ -408,6 +408,18 @@ public Quantity subtract(Quantity y) {
     return op(y, BigDecimal::subtract);
   }
 
+  /**
+   * Multiplies the quantity by the specified scalar multiplicand.
+   *
+   * @param multiplicand the scalar value to multiply by
+   * @return a new Quantity resulting from the multiplication of this quantity by the scalar multiplicand
+   */
+  public Quantity multiply(int multiplicand) {
+    BigDecimal numericalAmount = getNumericalAmount();
+    numericalAmount = numericalAmount.multiply(BigDecimal.valueOf(multiplicand));
+    return fromNumericalAmount(numericalAmount, format);
+  }
+
   Quantity op(Quantity y, BiFunction<BigDecimal, BigDecimal, BigDecimal> func) {
     BigDecimal numericalAmount = this.getNumericalAmount();
     numericalAmount = func.apply(numericalAmount, y.getNumericalAmount());

kubernetes-model-generator/kubernetes-model-core/src/test/java/io/fabric8/kubernetes/api/model/QuantityTest.java

@@ -222,4 +222,12 @@ void testSubtract() {
     Quantity quantity = new Quantity("0Mi");
     assertThat(quantity.subtract(new Quantity("1Ki"))).isEqualTo(new Quantity("-1Ki"));
   }
+
+  @Test
+  void testMultiply() {
+    Quantity quantity = new Quantity("4Gi");
+    assertThat(quantity.multiply(0)).isEqualTo(new Quantity("0"));
+    assertThat(quantity.multiply(3)).isEqualTo(new Quantity("12Gi"));
+    assertThat(quantity.multiply(-3)).isEqualTo(new Quantity("-12Gi"));
+  }
 }