private String getApiIdx(String orgId, String apiId, String version) {
        return "API::" + orgId + "|" + apiId + "|" + version; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
    }
Generates an in-memory key for an API, used to index the app for later quick
retrieval.
@param orgId
@param apiId
@param version
@return a API key
gateway/engine/es/src/main/java/io/apiman/gateway/engine/es/CachingEsRegistry.java