protected static class RigidShapeBuilder.AbstractShapeEntry
The AbstractShapeEntry class defines a shape entry in the AbstractShapeBuilderModel. Each entry contains an
instance of an AbstractShape, its associated editor and attributes, and state variables indicating whether the
entry is currently selected or being edited.
value - the attribute value. May be null, in which case any existing value for the key is
removed from the collection.
previous value associated with specified key, or null if there was no mapping for key. A null return can
also indicate that the map previously associated null with the specified key, if the implementation
supports null values.