private List<String> validateCasConfiguration() {
        return FunctionUtils.doAndHandle(() -> validateConfiguration(CasConfigurationProperties.class));
    }
Validate the cas configuration properties
from property sources found in the application
context and report back results..

@return the list
core/cas-server-core-configuration-api/src/main/java/org/apereo/cas/configuration/CasConfigurationPropertiesValidator.java