OpenAM FreeMarker template injection

OpenAM is an open access management solution. In versions 15.0.3 and prior, the getCustomLoginUrlTemplate method in RealmOAuth2ProviderSettings.java is vulnerable to template injection due to its usage of user input. Although the developer intended to implement a custom URL for handling login to override the default PingOne Advanced Identity Cloud login page,they did not restrict the CustomLoginUrlTemplate, allowing it to be set freely. Commit fcb8432aa77d5b2e147624fe954cb150c568e0b8 introduces TemplateClassResolver.SAFER_RESOLVER to disable the resolution of commonly exploited classes in FreeMarker template injection. As of time of publication, this fix is expected to be part of version 15.0.4.