Jetty 9.3 and 9.4 sometimes reset the connection too early in case of
errors, which leads to failing tests (UIInitExceptionTest,
AppResource404Test).

See e.g. https://issues.apache.org/jira/browse/SOLR-8453 for more
information.

Also fixed servlet API dependency scope that was causing conflicts.

* Add DragSource Extension (#8169)

* Add DropTarget Extension (#8170)

* Add DragStart Event to DragSource Extension (#8171)

* Make DataTransfer.dropEffect configurable (#8174)

* Make DragSource.dataTransfer data configurable (#8172)

* Add server-side Event for drop (#8177)

* Added license headers

* Extract handler methods, move DropEvent and DropListener to new file, move enums to top

* Replaced LinkedHashMap with Map and added List to preserve order of data

* Add API for adding a JS acceptance criteria for dragover and drop (#8178, #8179)

* Make DragSource Extension extendable (#8175)

* Make DropTarget Extension extendable (#8176)

* Added javadoc to protected methods

* Moved EffectAllowed to shared so that it could be used in shared state directly

* Moved DropEffect to separate file, some review fixes and javadoc

* Added list to DropTargetRpc to preserve order of data

* Remove event listeners on unregister

* Changed method names set/getData() to more descriptive set/getTransferData()

* Add server side dragStart event (#8171)

* Add style to prevent text selection to allow drag

* Remove target indicator style on drop

* Add client side dragend event listener for drag source

* Add server side dragend listener.
Attach client side listener only when server side listener added.

* Add drag source information to server side dragstart and dragend events.

* Fixed some issues addressed in review

* Trigger server side dragstart only when there is a listener attached

* Criteria script can be set as null to clear

* Use Js Interop instead of JSNI for handling event listeners

* Use elemental package instead of Js Interop for handling event listeners

* Add missing javadoc for public methods

* Add default value "uninitialized" to effectAllowed parameter

* Simple test UI for HTML5 DnD functionality (#8395)

* Add javadoc and other minor changes

Fixes #8522

Include Vaadin-Icons into the valo theme in the project,
make vaadin-icons dependency 'provided'

Fixes #8471

Don't implement handlers on widget level.

* Add clear field values #8287

Added functionality to make it possible to clear bound field values manually
or when setting a null bean to binder.

Binder will now clear bound fields for setBean(null) or if using readBean() functionality
when calling the clear() method. Binder.clear() will throw a IllegalStateException if
we have a bound bean.

* MultiSelectionModel MultiSelect should implement emptyValue

* Removing public clear() method and clearing field values only through
setBean(null) and readBean(null) to be consistent and not have
confusing functionality.

* Simplified clearFields() as we don't need to check if field is readOnly

* Document in removeBean JavaDoc that it will also clear the bound fields
if we have a bean the is removed.

* Binder should not have changes after clearing fields.

* Add getEmptyValue as default to MultiSelect.
Multiselect default for empty value should be an empty set.

* Revert "Add getEmptyValue as default to MultiSelect."

This reverts commit 45de8f45c4.

* Merge branch 'master' into issue/8287_Clear_bound_fields

* Remove override for default implementation.

* Fire status change event on clearFields if we had changes before clearing.

* Formatting.

* Fix JBoss 6 integration test
* Fixes for Karaf (build self-contained WAB)

Fixes #8489

Fixes #8357

Fixes #8488

Fixes #8422

* Added column should also be added to footer (#590)

When adding (readding) a column the column should also be
added to footer as it will be removed and iterator will request footer for it.

* Add test for re-add column (#590)

* To lowerCase using Locale

* Fixed compilation problem.
Too little sleep for a friday evening...

This patch also provides a documentation for #8382.

Fixes #8390

@NotNull, @Size(min>1), @NotEmpty annotations are handled via default
configuration which marks fields as required.

Fixes #8382

Also removes the confusing SerializableComparator.asInstance method that
was mainly introduced for internal use.

Fixes #8367

Fixes vaadin/framework8-issues#463

* Throw if there are no automatically bound fields via bindInstanceFields.

Fixes #8362

* Add Grid.addColumn(String, Renderer)

Fixes  #8405

* Added missing parametrisation onto the column field of the GridContextClickEvent.

Fixes vaadin/framework8-issues#594

Fixes #7250

Fixes #8371
Fixes #8128

* Fix problem with re-opening the popup (#8446)

Fixed problem that disables opening of popup
after closing it by clicking the datefield-button.

* Fix issue #8446 in compatibility version PopupDateField also.

Schedule column ordering so that possible onUnregister methods get run first.

* Add isValid to Binder

isValid enables you to check the current validation
status of a given Binder, without firing events or invoking
handlers.

This patch also clarifies the javadocs of StatusChangeEvents'
hasValidationErrors.

* Throw in Binder.isValid if no bean is set and bean validators exist

* Add test cases to BinderTest

* Add selection methods to grid that delegate to the selection model

* Merge remote-tracking branch 'github/master' into 577-alt

* Remove getFirstSelected, isSelected

Fix test checking for left:auto by testing the actual wrapper width
that should change.