private static Map readAccountsFromFile(final File json) throws Exception {
        return MAPPER.readValue(json, Map.class);
    }
This is {@link JsonResourceSurrogateAuthenticationService}.

@author Misagh Moayyed
@since 5.1.0
support/cas-server-support-surrogate-core/src/main/java/org/apereo/cas/authentication/surrogate/JsonResourceSurrogateAuthenticationService.java