code: public Variable createPipelineScheduleVariable(Object projectIdOrPath, Integer pipelineScheduleId,
              String key, String value) throws GitLabApiException {
  
          GitLabApiForm formData = new GitLabApiForm()
                  .withParam("key", key, true)
                  .withParam("value", value, true);
          Response response = post(Response.Status.CREATED, formData,
                  "projects", getProjectIdOrPath(projectIdOrPath), "pipeline_schedules", pipelineScheduleId, "variables");
          return (response.readEntity(Variable.class));
      }
docs: Create a pipeline schedule variable.
  
  <pre><code>GitLab Endpoint: POST /projects/:id/pipeline_schedules/:pipeline_schedule_id/variables</code></pre>
  
  @param projectIdOrPath projectIdOrPath the project in the form of an Integer(ID), String(path), or Project instance, required
  @param pipelineScheduleId the pipelineSchedule ID
  @param key the key of a variable; must have no more than 255 characters; only A-Z, a-z, 0-9, and _ are allowed
  @param value the value for the variable
  @return a Pipeline instance with the newly created pipeline schedule variable
  @throws GitLabApiException if any exception occurs during execution