Add required fix

Author: tharikaGitHub

components/apimgt/org.wso2.carbon.apimgt.impl/src/main/java/org/wso2/carbon/apimgt/impl/APIConsumerImpl.java

@@ -3757,7 +3757,8 @@ private Map<String, String> getHostWithSchemeMappingForEnvironment(API api, Stri
 
             boolean isExternalGateway = false;
             GatewayDeployer gatewayDeployer = null;
-            if (api.isInitiatedFromGateway()) {
+            if (gatewayConfiguration != null && StringUtils.isNotEmpty(
+                    gatewayConfiguration.getDiscoveryImplementation()) && api.isInitiatedFromGateway()) {
                 Map<String, String> extractedURLs = extractEndpointUrlsForDiscoveredApi(api);
                 if (extractedURLs == null) {
                     if (StringUtils.containsIgnoreCase(api.getTransports(), APIConstants.HTTP_PROTOCOL)) {