Detects non-existing encryption methods references in OpenTofu encryption block configuration. For the following code:

    
      terraform {
        encryption {
          key_provider "pbkdf2" "foo" {
            # Configuration parameters
          }
          method "aes_gcm" "yourname2" {
            keys = key_provider.pbkdf2.foo
          }
        }
      }
    
  

See https://opentofu.org/docs/language/state/encryption/#methods for more information.