Fix build issue with jaxrs-spec-microprofile-openapi-annotations sample

Author: Jurrie

samples/server/petstore/jaxrs-spec-microprofile-openapi-annotations/pom.xml

@@ -22,6 +22,7 @@
     <surefire-plugin.version>2.22.1</surefire-plugin.version>
     <javax.ws.rs-version>2.1.1</javax.ws.rs-version>
     <javax.annotation-api-version>1.3.2</javax.annotation-api-version>
+    <jackson-databind-nullable-version>0.2.8</jackson-databind-nullable-version>
   </properties>
   <dependencyManagement>
     <dependencies>
@@ -64,6 +65,11 @@
        <artifactId>javax.annotation-api</artifactId>
        <version>${javax.annotation-api-version}</version>
     </dependency>
+    <dependency>
+        <groupId>org.openapitools</groupId>
+        <artifactId>jackson-databind-nullable</artifactId>
+        <version>${jackson-databind-nullable-version}</version>
+    </dependency>
   </dependencies>
   <build>
     <plugins>