[559231] Blank metamodel generation

This commit is just a generation without any change. It was done with
this configuration:
* Eclipse 2019-12
* Formatter : "Eclipse [built-in]"
* Clean up : "Eclipse [built-in] - Without Annotations" (a copy of
  "Eclipse [built-in]" but with "Annotations" disabled to avoid
  compilation problem with "typed" list (tab "Missing Code" unckeck "Add
  missing Annotations").
* EMF 2.20 (EMF - Eclipse Modeling Framework SDK 2.20.0.v20191028-0905)

The generation was done:
* using "Generate Model Code" and "Generation Edit Code" actions from
  notation.genmodel
* and then launching "Clean up" on src folders of
  org.eclipse.gmf.runtime.notation and
  org.eclipse.gmf.runtime.notation.edit.

There are some javadoc and comment changes.
There is no real java changes except the following, but explained by
expected EMF generator changes:
* org.eclipse.gmf.runtime.notation.impl.NodeEntryImpl
* org.eclipse.gmf.runtime.notation.impl.NotationFactoryImpl
* org.eclipse.gmf.runtime.notation.impl.NotationPackageImpl
* org.eclipse.gmf.runtime.notation.impl.ShapeStyleImpl

Bug: 559231
Change-Id: I87b44809403004dfce611e5537f312c05ab585e2
Signed-off-by: Laurent Redor <laurent.redor@obeo.fr>
Also-by: Pierre-Charles David <pierre-charles.david@obeo.fr>