IntegrityProtection when using OpenPGP ECDH keys

Hi!

I noticed, that the call

bcPGPDataEncryptorBuilder.setWithIntegrityPacket(true);

appears to be broken when I encrypt for an ECDH public key.
The same call works fine when RSA keys are used, meaning the call

pgpPublicKeyEncryptedData.isIntegrityProtected();

returns true. However, it returns false when ECDH keys are used.
Is this a bug, or expected behaviour?

I know that elliptic curve keys are not really specified in RFC4880,
but I found a specification in RFC6637, which also mentions the
integrity protection package.

Greetings Paul