How to set object list to Vaadin 8 combobox

I want to integrate list of complex objects to a Vaadin combobox. I tried it as follows and that shows only garbage values (toString() values). But I want to know how to set the specific attribute which should show in the drop down.

Below class objects should be rendered in the combobox.

public class TestExecution {
private String name;
private String startingTime;
private String endingTime;
private String status;

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getStartingTime() {
    return startingTime;
}

public void setStartingTime(String startingTime) {
    this.startingTime = startingTime;
}

public String getEndingTime() {
    return endingTime;
}

public void setEndingTime(String endingTime) {
    this.endingTime = endingTime;
}

public String getStatus() {
    return status;
}

public void setStatus(String status) {
    this.status = status;
}

}

Note: I can't override the toString() method as I will be using it for other purposes.