Fix invalid message in OpenAPI gen client

misc/openapi-ballerina/modules/openapi-to-ballerina-generator/src/main/java/org/ballerinalang/openapi/CodeGenerator.java

@@ -89,17 +89,14 @@ private void generate(GenType type, String executionPath, String definitionPath,
             throws IOException, BallerinaOpenApiException {
 
         if (!CodegenUtils.isBallerinaProject(Paths.get(outPath))) {
-            throw new BallerinaOpenApiException("Output path is not a valid ballerina project directory. Use "
-                    + "'ballerina init' to generate a new project");
+            throw new BallerinaOpenApiException(OpenApiMesseges.GEN_CLIENT_PROJECT_ROOT);
         }
 
         //Check if the selected path is a ballerina root for service generation
         //TODO check with team for root check
         Path projectRoot = ProjectDirs.findProjectRoot(Paths.get(executionPath));
         if (type.equals(GenType.GEN_SERVICE) && projectRoot == null) {
-            throw LauncherUtils.createUsageExceptionWithHelp("Ballerina service generation should be done " +
-                    "from the project root. If you like to start with a new project use `ballerina init` command to " +
-                    "create a new project.");
+            throw LauncherUtils.createUsageExceptionWithHelp(OpenApiMesseges.GEN_SERVICE_PROJECT_ROOT);
         }
 
         Path srcPath = CodegenUtils.getSourcePath(srcPackage, outPath);

misc/openapi-ballerina/modules/openapi-to-ballerina-generator/src/main/java/org/ballerinalang/openapi/OpenApiMesseges.java

@@ -39,7 +39,8 @@ public class OpenApiMesseges {
             " order generate an OpenApi contract for the service \nballerina openapi gen-contract " +
             "[moduleName]:serviceName [-i: ballerinaFile]";
 
-
+    public static final String GEN_CLIENT_PROJECT_ROOT = "Output path is not a valid ballerina project directory." +
+            "\nUse 'ballerina new' to generate a new project";
     public static final String GEN_SERVICE_MODULE_ARGS_REQUIRED = "A module name and a service name is required " +
             "in order to generate the ballerina service for the provided OpenApi contract. \nE.g. ballerina " +
             "openapi gen-service <module_name>:<service_name> <openapi_contract>";