Cipher algorithm not found in recipient preferences

[adeftu]

I wrote a PGP encryption Java function similar to the one provided in the example here:

bc-java/pg/src/main/java/org/bouncycastle/openpgp/examples/ByteArrayHandler.java

Line 119 in 92f2dd8

public static byte[] encrypt(

I want to use this function to mimic the current behaviour of encrypting via GNU gpg:

# encrypt
cat gpg_public.key | gpg --import --batch
cat data.txt | gpg --output encrypted_data.out --encrypt --armor --batch --always-trust --recipient "[email protected]"

# decrypt
cat gpg_private.key | gpg --import --batch
gpg --output decrypted_data.txt --decrypt --armor encrypted_data.out

Decrypting the file encrypted via this Java function seems to work, but I'm getting the following warning:

gpg: WARNING: cipher algorithm IDEA not found in recipient preferences
gpg: encrypted with 2048-bit RSA key, ID E34D465861FEBE98, created 2020-06-29
      "Test User <[email protected]>"

This warning is not shown when the input file is encrypted via GNU gpg command line. Any idea why? What would be the equivalent of --recipient in Bouncy Castle? Couldn't find a way to specify this recipient in the encryption function. I wonder if that's the reason.