add the comment to unit test

Signed-off-by: kkewwei <kkewwei@163.com>

Author: kkewwei

server/src/test/java/org/opensearch/common/settings/SettingTests.java

@@ -201,7 +201,7 @@ public void testMemorySize() {
         assertEquals(new ByteSizeValue(12), value.get());
 
         assertTrue(settingUpdater.apply(Settings.builder().put("a.byte.size", "20%").build(), Settings.EMPTY));
-        assertEquals(new ByteSizeValue((int) (JvmInfo.jvmInfo().getMem().getHeapMax().getBytes() * 0.2)), value.get());
+        assertEquals(new ByteSizeValue((long) (JvmInfo.jvmInfo().getMem().getHeapMax().getBytes() * 0.2)), value.get());
     }
 
     public void testMemorySizeWithFallbackValue() {
@@ -219,6 +219,8 @@ public void testMemorySizeWithFallbackValue() {
         assertEquals(memorySizeValue.getBytes(), JvmInfo.jvmInfo().getMem().getHeapMax().getBytes() * 0.2, 1.0);
 
         assertTrue(settingUpdater.apply(Settings.builder().put("a.byte.size", "30%").build(), Settings.EMPTY));
+        // If value=getHeapMax()*0.3 is bigger than 2gb, and is bigger than Integer.MAX_VALUE,
+        // then (long)((int) value) will lose precision.
         assertEquals(new ByteSizeValue((long) (JvmInfo.jvmInfo().getMem().getHeapMax().getBytes() * 0.3)), value.get());
 
         assertTrue(settingUpdater.apply(Settings.builder().put("b.byte.size", "40%").build(), Settings.EMPTY));