The custom header added in #1695 was a single name/value pair, which is
enough for a proxy that authenticates with one token but not for Pangolin,
which expects both P-Access-Token-Id and P-Access-Token.
NTFY_CUSTOMHEADER_NAME and NTFY_CUSTOMHEADER_VALUE are replaced by a single
list setting, NTFY_CUSTOM_HEADERS, holding one "Name: Value" entry per
header. The list widget is the same one the other list settings use.
Only the first colon separates the name from the value, so values may
contain colons. An entry is skipped and logged when it is malformed, when
the name repeats, or when it collides with a header the plugin already set,
so a custom header still cannot clobber the ntfy credentials.
Values are never written to the log, since they are usually secrets. That
also applies to the invalid-header error, which now names the headers that
were applied without quoting any of them.
Aditya Raj Singh
4f604e4e2b