[BUG] [Helidon] JsonNullable issue

[aserkes]

Description

• Import org.openapitools.jackson.nullable.JsonNullable and related maven dependency are added in server generators even if jsonb is used as a serialization library.
• Duplicate imports of this class are found in client generators when jackson is used.

openapi-generator version

Openapi-generator: 6.5.0
Helidon version: 3.0.1

OpenAPI declaration file content or url

Error occurs with any OpenAPI declaration file.

Generation Details

Client generator issue :

java -jar  openapi-generator-cli.jar \
generate \
-g java-helidon-client \
--library se \
-i petstore.yaml \
-p groupId=me.mytest-helidon \
-p artifactId=mytest-helidon-se-client \
-p artifactVersion=1.0.0-SNAPSHOT \
-p dateLibrary=java8 \
-p serializationLibrary=jackson
mvn clean package

Server generator issue :

java -jar  openapi-generator-cli.jar \
generate \
-g java-helidon-server \
--library se \
-i petstore.yaml \
-p groupId=me.mytest-helidon \
-p artifactId=mytest-helidon-se-client \
-p artifactVersion=1.0.0-SNAPSHOT \
-p dateLibrary=java8 \
-p serializationLibrary=jsonb
mvn clean package

Related issues/PRs

helidon-io/helidon#6660