Added a method to remove the extensions

[slinkydeveloper]

Fix #215

cc @johanhaleby

Signed-off-by: Francesco Guardiani francescoguard@gmail.com

[johanhaleby]

Would it make sense to have a method such as public SELF withoutExtension(@Nonnull Extension extension) to remove all properties of an extension?

[slinkydeveloper]

@johanhaleby what about now?

[johanhaleby]

👍

But I think it would be great to also add an equals check (psuedo code from memory :)):

CloudEvent a = CloudEventBuilder.v1().withId("id").withExtension(myExtension).build();
CloudEvent b = CloudEventBuilder.v1(a).withoutExtension(myExtension).build();

assertThat(a).isEqualTo(b);