title: 7.1 migration and Progress Indicator
body: <p>I'm moving to 7.1 from 7.0.5 version and I begin to change ProgressIndicator class with ProgressBar to refactor with the new polling mechanism.</p>
  
  <p>This is returned error:</p>
  
  <p>Caused by: java.lang.NoSuchMethodError: com/vaadin/ui/AbstractField.getState(Z)Lcom/vaadin/shared/AbstractFieldState;
      at com.vaadin.ui.ProgressBar.getState(ProgressBar.java:108)
      at com.vaadin.ui.ProgressBar.getState(ProgressBar.java:33)
      at com.vaadin.ui.AbstractComponent.isReadOnly(AbstractComponent.java:535)
      at com.vaadin.ui.AbstractField.isReadOnly(AbstractField.java:201)
      at com.vaadin.ui.AbstractField.setValue(AbstractField.java:457)
      at com.vaadin.ui.AbstractField.setValue(AbstractField.java:438)
      at com.vaadin.ui.ProgressBar.setValue(ProgressBar.java:93)
      at com.vaadin.ui.ProgressBar.(ProgressBar.java:50)
      at com.vaadin.ui.ProgressBar.(ProgressBar.java:40)</p>
  
  <p>Anybody can explain me?</p>
  
  <p>Thanks</p>