Existing javadoc of Cipher.getParameters()/CipherSpi.engineGetParameters() can use some update:
1) syntax-wise: see JDK-8206171 changes in Signature.getParameters/SignatureSpi.engineGetParameters()
2) meaning of null: consider to allow null to be returned if providers cannot generate default parameters. Just as the changes of JDK-8206171.
3) accommodate algorithm-specific/provider-specific implementation on how parameters is handled. For example, in PBE-based Cipher, one can only include salt and iteration count in the init params, and init() will add in a random IV, and then parameters is retrieved with getParameters().