warning: [unchecked] unchecked method invocation on creating a a custom Selenium ExcpectedCondition

I am trying to create a custom Selenium explicit wait with the following code

class TabsOpened implements ExpectedCondition {     
int expectedTabs;
  
public TabsOpened(int exp) {
  this.expectedTabs = exp;  
}
  
@Override
public Boolean apply(Object driver) {       
  ArrayList<String> allWindowHandles = new ArrayList<> (((WebDriver)driver).getWindowHandles()); 
  return allWindowHandles.size()== this.expectedTabs;
} 
}

then

wait.until(new TabsOpened(2));

But I am getting these warnings while compilation

Note: Tests.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

Compiling with -Xlint:unchecked flag I get

Tests.java:116: warning: [unchecked] unchecked method invocation: method until in class FluentWait is applied to given types
            wait.until(new TabsOpened(2));  // Wait 3 seconds or until 2 tabs are opened
                      ^
  required: Function<? super T,V>
  found: TabsOpened
  where T,V are type-variables:
    T extends Object declared in class FluentWait
    V extends Object declared in method <V>until(Function<? super T,V>)
Tests.java:116: warning: [unchecked] unchecked conversion
            wait.until(new TabsOpened(2));  // Wait 3 seconds or until 2 tabs are opened
                       ^
  required: Function<? super T,V>
  found:    TabsOpened
  where T,V are type-variables:
    T extends Object declared in class FluentWait
    V extends Object declared in method <V>until(Function<? super T,V>)

Any ideas on how to fix that? I am using Selenium 2.53

Answer

I’m not familiar with this framework but according to the javadoc of the interface you are extending, you should write implements ExpectedCondition<Boolean> and the parameter of the overridden method should be of type WebDriver, not Object.