[BUG] Unable to start mirth client over ZTNA Proxy for mirth 4.0.0 or higher

[MichaelLeeHobbs]

Describe the bug
A clear and concise description of what the bug is. Is this consistently reproducible? Yes

Unable to start mirth client over ZTNA Proxy for mirth 4.0.0 or higher. Mirth 3.7.1 has no issue. Each user could have a different port assigned to Mirth. For example: https://localhost:10002/webstart when you try to launch from the MCAL you get the following error.

With Mirth 3.7.1 when the Mirth login screen pops up you have to retype the correct port, which is annoying but acceptable.

Unable to retrieve payload from HTTP request. URI: https://localhost:8443/webstart/extensions/scriptfilestep.jnlp
java.lang.Exception: Unable to retrieve payload from HTTP request. URI: https://localhost:8443/webstart/extensions/scriptfilestep.jnlp
	at com.mirth.connect.client.launcher.f.a(SourceFile:791)
	at com.mirth.connect.client.launcher.f.a(SourceFile:671)
	at com.mirth.connect.client.launcher.f.a(SourceFile:305)
	at com.mirth.connect.client.launcher.MirthClientLauncher.run(SourceFile:1230)
	at java.lang.Thread.run(Unknown Source)

To Reproduce
Steps to reproduce the behavior:

1. netsh interface portproxy add v4tov4 listenaddress=127.0.0.1 listenport=10002 connectaddress=mirth.address connectport=8443
2. Launch mirth via MCAL https://localhost:10002/webstart

Expected behavior
In general, Mirth handles proxies poorly and does not respect proxy headers, see: #4808 #4467 #4220 #1779. Proxies, Load Balancers, and WAF, are everywhere today. MCAL and Connect need to do a better job handling proxies and HTTP Headers related to proxies/load balancers. ZTNA, adoption is picking up speed, and depending on how the specific ZTNA handles pinhole access this will become more of a problem.

Actual behavior
Should work seamlessly with correctly configured Proxies, Load Balancers, and WAF.

Screenshots
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Environment (please complete the following information):

• OS: [e.g. Linux (CentOS), Windows 10, MacOS]
• Java Distribution/Version [e.g. OpenJDK 11, Java 8 (201)]
• Connect Version [e.g. 3.8.0]

Workaround(s)
Are there one or more workarounds for this issue currently?

Additional context
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