finalizepsbt "psbt" ( extract )
Finalize the inputs of a PSBT. If the transaction is fully signed, it will produce a
network serialized transaction which can be broadcast with sendrawtransaction. Otherwise a PSBT will be
created which has the final_scriptSigfields filled for inputs that are complete.
Implements the Finalizer and Extractor roles.

1. psbt       (string, required) A base64 string of a PSBT
2. extract    (boolean, optional, default=true) If true and the transaction is complete,
              extract and return the complete transaction in normal network serialization instead of the PSBT.

  "psbt" : "value",          (string) The base64-encoded partially signed transaction if not extracted
  "hex" : "value",           (string) The hex-encoded network transaction if extracted
  "complete" : true|false,   (boolean) If the transaction has a complete set of signatures

> bitcoin-cli finalizepsbt "psbt"