output: #fixed code
                                  private void testHealthCheck(Predicate<Connection> healthy) throws InterruptedException {
          TestScheduler scheduler = new TestScheduler();
  
          NonBlockingConnectionPool2 pool = Pools //
                  .nonBlocking() //
                  .connectionProvider(DatabaseCreator.connectionProvider()) //
                  .maxIdleTime(10, TimeUnit.MINUTES) //
                  .idleTimeBeforeHealthCheck(0, TimeUnit.MINUTES) //
                  .healthy(healthy) //
                  .returnToPoolDelayAfterHealthCheckFailure(1, TimeUnit.MINUTES) //
                  .scheduler(scheduler) //
                  .maxPoolSize(1) //
                  .build();
  
          try (Database db = Database.from(pool)) {
              TestSubscriber<Integer> ts0 = db.select( //
                      "select score from person where name=?") //
                      .parameter("FRED") //
                      .getAs(Integer.class) //
                      .test();
              ts0.assertValueCount(0) //
                      .assertNotComplete();
              scheduler.advanceTimeBy(1, TimeUnit.MINUTES);
              ts0.assertValueCount(1) //
                      .assertComplete();
              TestSubscriber<Integer> ts = db.select( //
                      "select score from person where name=?") //
                      .parameter("FRED") //
                      .getAs(Integer.class) //
                      .test() //
                      .assertValueCount(0);
              System.out.println("done2");
              scheduler.advanceTimeBy(1, TimeUnit.MINUTES);
              Thread.sleep(200);
              ts.assertValueCount(1);
              Thread.sleep(200);
              ts.assertValue(21) //
                      .assertComplete();
          }
      }
input: #vulnerable code 
                                  private void testHealthCheck(Predicate<Connection> healthy) throws InterruptedException {
          TestScheduler scheduler = new TestScheduler();
  
          NonBlockingConnectionPool pool = Pools //
                  .nonBlocking() //
                  .connectionProvider(DatabaseCreator.connectionProvider()) //
                  .maxIdleTime(10, TimeUnit.MINUTES) //
                  .idleTimeBeforeHealthCheck(0, TimeUnit.MINUTES) //
                  .healthy(healthy) //
                  .returnToPoolDelayAfterHealthCheckFailure(1, TimeUnit.MINUTES) //
                  .scheduler(scheduler) //
                  .maxPoolSize(1) //
                  .build();
  
          try (Database db = Database.from(pool)) {
              TestSubscriber<Integer> ts0 = db.select( //
                      "select score from person where name=?") //
                      .parameter("FRED") //
                      .getAs(Integer.class) //
                      .test();
              ts0.assertValueCount(0) //
                      .assertNotComplete();
              scheduler.advanceTimeBy(1, TimeUnit.MINUTES);
              ts0.assertValueCount(1) //
                      .assertComplete();
              TestSubscriber<Integer> ts = db.select( //
                      "select score from person where name=?") //
                      .parameter("FRED") //
                      .getAs(Integer.class) //
                      .test() //
                      .assertValueCount(0);
              System.out.println("done2");
              scheduler.advanceTimeBy(1, TimeUnit.MINUTES);
              Thread.sleep(200);
              ts.assertValueCount(1);
              Thread.sleep(200);
              ts.assertValue(21) //
                      .assertComplete();
          }
      } 
                              #location 15 
                              #vulnerability type RESOURCE_LEAK