VaultEncryptionHelper's validation exception message should include all validation problems

[sleberknight]

The ValidationEncryptionHelper constructor validates its arguments. When it validates the VaultConfiguration it throws an IllegalArgumentException for the first problem it finds. So, if there is more than one problem, the calling code won't know that and will only know about the first problem.

It would be much better to validate the entire object and provide a message containing all the validation errors in the IllegalArgumentException's message.

VaultConfiguration uses the @NotBlank Java/Jakarta Beans Validation annotation on its properties, though it does not validate that those paths actually exist. However, ValidationEncryptionHelper does not use Beans Validation to validate, but checks the properties itself. IIRC the Beans Validation annotations were mainly to allow the VaultConfiguration to be validated at (Dropwizard) service startup, since it would be part of the service configuration class. The more involved validation inside ValidationEncryptionHelper also verifies that the specified files (e.g. the ansible-vault executable and the vault password file) actually exist.

Regardless of how we choose to implement the validation in ValidationEncryptionHelper, the IllegalArgumentException should contain all the problems.