@Override
        public String lookup(@NonNull final String key) {
            try {
                return new String(Files.readAllBytes(Paths.get(key)), StandardCharsets.UTF_8);
            } catch (IOException | InvalidPathException e) {
                LOGGER.log(
                        Level.WARNING,
                        String.format(
                                "Configuration import: Error looking up file '%s' with UTF-8 encoding. Will default to empty string",
                                key),
                        e);
                return null;
            }
        }
Resolve string with potential secrets

@param toInterpolate potential variables that need to revealed
@return original string with any secrets that could be resolved if secrets could not be
resolved they will be defaulted to default value defined by ':-', otherwise default to empty
String. Secrets are defined as anything enclosed by '${}'
plugin/src/main/java/io/jenkins/plugins/casc/SecretSourceResolver.java