SP upgrade 2.3.1 to 2.4.3: disable signature validation of xml metadata?

[jacob at collegenet.com]

Hello,

We are attempting to upgrade from SP version 2.3.1 (Debian squeeze) to version 2.4.3 (Debian wheezy) and running into a problem where we can't seem to avoid signature validation of metadata loads.  Some IdPs we work with do not provide metadata with valid signatures.  Therefore our configuration for them looks like this:

<MetadataProvider type="XML" uri="https://host.com/path/to/metadata.xml" backingFilePath="metadata-host.xml" reloadInterval="7200">
    <TrustEngine type="StaticPKIX" certificate="/etc/ssl/certs/ca-certificates.crt" verifyDepth="2"/>
</MetadataProvider>

In the 2.3.1 SP this results in log messages like the following during start-up:

2013-06-14 13:18:12 INFO OpenSAML.MetadataProvider.XML [995]: reloading remote resource...
2013-06-14 13:18:12 INFO OpenSAML.MetadataProvider.XML [995]: loaded XML resource (https://host.com/path/to/metadata.xml)

But in the 2.4.3 SP instead we get something like this:

2013-06-14 17:25:36 INFO OpenSAML.MetadataProvider.XML : reload thread started...running every 600 seconds
2013-06-14 17:25:37 INFO OpenSAML.MetadataProvider.XML : loaded XML resource (https://host.com/path/to/metadata.xml)
2013-06-14 17:25:37 ERROR OpenSAML.MetadataProvider.XML : error while loading resource (https://host.com/path/to/metadata.xml): Signature validation required, but no signature found.
2013-06-14 17:25:37 WARN OpenSAML.MetadataProvider.XML : adjusted reload interval to 600 seconds
2013-06-14 17:25:37 INFO OpenSAML.MetadataProvider.XML : using local backup of remote resource
2013-06-14 17:25:37 ERROR XMLTooling.ParserPool : fatal error on line 0, column 0, message: unable to open primary document entity '/var/run/shibboleth/metadata-host.xml'
2013-06-14 17:25:37 ERROR OpenSAML.MetadataProvider.XML : error while loading resource (/var/run/shibboleth/metadata-host.xml): XML error(s) during parsing, check log for specifics
2013-06-14 17:25:37 CRIT OpenSAML.Metadata.Chaining : failure initializing MetadataProvider: XML error(s) during parsing, check log for specifics

(The validation error of course varies; sometimes instead of "no signature" it is "Invalid signature profile" ... either way the metadata is not loaded like it was in 2.3.1.)

I spent a while googling around for information about disabling signature validation in the SP but could not find anything relevant.  Any suggestions are greatly appreciated.

Thanks,
-Jacob