protected InputStream getResourceInputStream(final Resource resource, final String entityId) throws IOException {
        LOGGER.debug("Locating metadata resource from input stream.");
        if (!resource.exists() || !resource.isReadable()) {
            throw new FileNotFoundException("Resource does not exist or is unreadable");
        }
        return resource.getInputStream();
    }
Build metadata resolver aggregate. Loops through metadata resources
and attempts to resolve the metadata.

@param entityId the entity id
support/cas-server-support-saml-mdui-core/src/main/java/org/apereo/cas/support/saml/mdui/AbstractMetadataResolverAdapter.java