Mutation query with Joined Inheritance for databases supporting Global Temporary Tabels

[dreab8]

Given :

@Entity(name = "GeneratedWithIdentityParent")
	@Inheritance(strategy = InheritanceType.JOINED)
	static class GeneratedWithIdentityParent {
		@Id
		@GeneratedValue(strategy = GenerationType.IDENTITY)
		public Long id;

		public String firstname;
	}

	@Entity(name = "GeneratedWithIdentity")
	static class GeneratedWithIdentity extends GeneratedWithIdentityParent {
		public String updatedBy;
	}

the test

@Test
	public void testInsert(VertxTestContext context) {
		String firstName ="Davide";
		test( context, getMutinySessionFactory()
			.withTransaction( session ->
				session.createMutationQuery( "insert into GeneratedWithIdentity (firstname) values (:name)" )
				.setParameter( "name", firstName )
				.executeUpdate())
		);
	}

fails when executed against Oracle with the following error

Cannot invoke "java.util.concurrent.CompletionStage.toCompletableFuture()" because the 
return value of "java.util.function.Function.apply(Object)" is null
java.lang.NullPointerException: Cannot invoke "java.util.concurrent.CompletionStage.toCompletableFuture()" 
because the return value of "java.util.function.Function.apply(Object)" is null