@Test
    public void resolve_FileNotFound() {
        resolve("${readFile:./hello-world-not-found.txt}");
        assertTrue(logContains(
                "Configuration import: Error looking up file './hello-world-not-found.txt' with UTF-8 encoding."));
        assertTrue(
                logContains("Configuration import: Found unresolved variable 'readFile:./hello-world-not-found.txt'."));
    }
Ensures that prefixes in the secret ID which are not covered by the CasC protocol substitutors (e.g. base64:, file:)
are left untouched and not removed.
plugin/src/test/java/io/jenkins/plugins/casc/SecretSourceResolverTest.java