minor wording changes (#316)

Signed-off-by: David Kral <david.k.kral@oracle.com>

Author: Verdent

api/src/main/java/jakarta/json/bind/annotation/JsonbTypeInfo.java

@@ -33,7 +33,7 @@
  * class Dog implements Animal {}
  * class Cat implements Animal {}
  * </code></pre>
- * This annotation is tightly bound to {@link JsonbSubtype}. It is recommended to use
+ * This annotation is tightly bound to {@link JsonbSubtype}. It is required to use
  * {@link JsonbSubtype} annotations to specify all the possible classes and their aliases.
  */
 @JsonbAnnotation

spec/src/main/asciidoc/jsonb.adoc

@@ -699,7 +699,7 @@ If a required field for a parameter mapping does not exist in the JSON document,
 
 [[optional-parameter-values]]
 ==== Optional parameter values
-When a property is marked as optional, the proper default should be used. If the parameter is any type other than `Optional` or its variations, then the `null` value is used. If the parameter is `Optional` or its variations, then the corresponding empty object must be used.
+When a property is marked as optional, the proper default should be used. If the parameter is any type other than `Optional` or its variations, then the `null` value is used. If the parameter is `java.util.Optional`, `OptionalInt`, `OptionalLong`, `OptionalDouble`, then the corresponding empty object must be used.
 
 Primitive types cannot accept `null` values, so a corresponding value is required as listed in the following table: