If you want to verify that the certificate chain is installed in the Gateway's web server from a module running on that same Gateway, you could open a TLS client connection targeting localhost and the Gateway's HTTPS port. Java's JSSE APIs expose hooks to inspect the certificate chain presented by the server (in this case, the Gateway web server) during the authentication portion of the TLS handshake. Use this hook to compare the chain presented by the Gateway matches what you expect (the chain you just installed).
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