{
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"plaintext_envelope": {
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"type": "req",
"seq": 0,
"method": "echo",
"params": { "a": 1, "b": 2 }
},
"canonical_json_hex": "7b226d6574686f64223a226563686f222c22706172616d73223a7b2261223a312c2262223a327d2c22736571223a302c2273747265616d5f6964223a312c2274797065223a22726571227d"
}
}