[BUG] [JAVA] validateJsonElement fails for required nullable fields #2845

Job	Run time
Gradle tests (samples/client/petstore/java/jersey2-java8)	51s
Gradle tests (samples/openapi3/client/extensions/x-auth-id-alias/java/jersey2-java8)	50s
Gradle tests (samples/client/petstore/java/native)	51s
Gradle tests (samples/client/petstore/java/jersey2-java8-localdatetime)	51s
Gradle tests (samples/client/petstore/java/native-jakarta)	51s
Gradle tests (samples/openapi3/client/petstore/java/jersey2-java8-special-characters)	51s
Gradle tests (samples/openapi3/client/petstore/java/jersey2-java8)	51s
Gradle tests (samples/client/petstore/java/okhttp-gson)	47s
Gradle tests (samples/client/petstore/java/okhttp-gson-group-parameter)	1s
Gradle tests (samples/client/petstore/java/webclient-swagger2)	50s
Gradle tests (samples/client/petstore/java/okhttp-gson)	1m 30s
Gradle tests (samples/openapi3/client/extensions/x-auth-id-alias/java/jersey2-java8)	1m 14s
Gradle tests (samples/client/petstore/java/jersey2-java8-localdatetime)	1m 22s
Gradle tests (samples/client/petstore/java/native)	1m 23s
Gradle tests (samples/client/petstore/java/webclient-swagger2)	1m 27s
Gradle tests (samples/client/petstore/java/native-jakarta)	1m 11s
Gradle tests (samples/openapi3/client/petstore/java/jersey2-java8)	1m 14s
Gradle tests (samples/client/petstore/java/jersey2-java8)	1m 17s
Gradle tests (samples/openapi3/client/petstore/java/jersey2-java8-special-characters)	1m 23s
Gradle tests (samples/client/petstore/java/okhttp-gson-group-parameter)	1m 20s
	20m 55s

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