Send multi-line SSH RSA Private Key in as Variable in JSON Body

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1

Sending Private RSA SSH Key in JSON Body - Unable to parse message body:

The problem:
I need to upload a private SSH key in ID_RSA format to the Oracle Cloud Infrastructure API. But when doing as example a cat command, I get a multi-line output of the SSH key in this format:

-----BEGIN RSA PRIVATE KEY-----
MIIG5AIBAAKCAYEAxYBpIbe7Vuc9cHDMwVQtN70GmA600dzQID7STCGwPwNG3ip1
qZL25vSGH9YJ4wWVm6Ui3EdGpNG4v4EkR/FAu7VmFYhzL4K1LP1uFynzdCYkwYhM
<REDACTED>
6CriS7d4/C8UjyQv6KuJM9JzeGODtCkoOAYifqzla2aupXwVRavASuAQ/6l3DCej
xpdSB9MY6Ty6sT5YYp6CZv14+LzkVoD7bwT7vaZooq1FuTiG4WzU8w==
-----END RSA PRIVATE KEY-----

When I copy & paste the out an want to use it as variable, for each line Postman creates a new line too. The POST command is unable to parse the load.

{
    "sshKey": "-----BEGIN RSA PRIVATE KEY-----
MIIG5AIBAAKCAYEAxYBpIbe7Vuc9cHDMwVQtN70GmA600dzQID7STCGwPwNG3ip1
qZL25vSGH9YJ4wWVm6Ui3EdGpNG4v4EkR/FAu7VmFYhzL4K1LP1uFynzdCYkwYhM
iFYO/jpPtn0R12Hq0Zh4vtyOW/BbdEJtHIq+d2mc69t3m6gZfx2pgQcPUFAn+zOu
c31ZN0E/F8CAv7h8H6kU2htwsuk+XPw4tM7qCH94Cqmc+JuSpQnMNcOoQGmYff2S
9DZ6+xcHaH1fhwtEgRQtt1N5sqQdbXYv0sbYlsuFSL+vNdRHl5yeGOys7M9PTbcM
<REDACTED>
}

The Postman error:

{
    "code": "InvalidParameter",
    "message": "Unable to parse message body"
}

How can I send this multi-line SSH key to the API? This is the link to the API definition:

https://docs.oracle.com/en-us/iaas/api/#/en/database-migration/20230518/datatypes/CreateOracleConnectionDetails

Any inputs are highly appreciated.

Thanks,
Martin