How to mock the Google Workflow call from Google-cloud-client-libraries in a unit test

Question

I am using Google Workflow from Google Cloud. I need to trigger the execution of a given Google Workflow from my java microservice.

My app is a Spring-boot application but I don't know if it matters.

The way I trigger the workflow is the following, based on the google documentation: https://cloud.google.com/workflows/docs/execute-workflow-client-libraries

        try (ExecutionsClient executionsClient = ExecutionsClient.create()) {
            WorkflowName workflow = WorkflowName.of(workflowProperties.getProjectId(), workflowProperties.getLocation(), workflowProperties.getName());
            
            Execution arguments = Execution.newBuilder().setArgument(String.format("{ \"executionId\": \"%s\" }", executionId)).build();
            CreateExecutionRequest request =
                    CreateExecutionRequest.newBuilder()
                            .setParent(workflow.toString())
                            .setExecution(arguments)
                            .build();
            Execution response = executionsClient.createExecution(request);
            if (!response.hasError()) {
                ... LOG everything is fine
            } else {
                ... LOG the error
            }

        } catch (Exception e) {
            ... LOG / handle exception
        }

In my unit/mockito test I get a 404 error because the test cannot reach google. I need to mock the actual call to Google, and to do this I probably need to mock ExecutionsClient.create().

This is a static call and I don't want to use powerMockito in my test to mock static stuff. Is there any other option?