Implement Extensible.hasExtension

Extensible.getExtension already has an implementation.

Allow hasExtension and getExtension to handle internal extensions, as
addExtension and removeExtension do. This means that they're not exactly
equivalent to getExtensions().hasKey and getExtensions().get.

model/src/main/java/io/smallrye/openapi/model/BaseExtensibleModel.java

@@ -237,6 +237,12 @@ public void setExtensions(Map<String, Object> extensions) {
         }
     }
 
+    @Override
+    public boolean hasExtension(String name) {
+        return extensionNames.contains(name);
+    }
+
+    @Override
     public Object getExtension(String name) {
         if (extensionNames.contains(name)) {
             return super.getProperty(name);

pom.xml

@@ -22,7 +22,7 @@
         <version.eclipse.microprofile.config>3.0.3</version.eclipse.microprofile.config>
         <version.io.smallrye.jandex>3.2.3</version.io.smallrye.jandex>
         <version.io.smallrye.smallrye-config>3.10.2</version.io.smallrye.smallrye-config>
-        <version.eclipse.microprofile.openapi>4.0.2</version.eclipse.microprofile.openapi>
+        <version.eclipse.microprofile.openapi>4.1-SNAPSHOT</version.eclipse.microprofile.openapi>
         <version.org.hamcrest>1.3</version.org.hamcrest>
         <version.org.hamcrest.java-hamcrest>2.0.0.0</version.org.hamcrest.java-hamcrest>
         <version.org.skyscreamer>1.5.3</version.org.skyscreamer>