An enumeration for keys used as client properties within the Swing implementation.

This enum holds only a small subset of the keys currently used within Swing, but we may move more of them here in the future.

Adding an item to, and using, this class instead of String for client properties protects against conflicts with developer-set client properties. Using this class also avoids a problem with StringBuilder and StringBuffer keys, whereby the keys are not recognized upon deserialization.

When a client property value associated with one of these keys does not implement Serializable, the result during serialization depends on how the key is defined here. Historically, client properties with values not implementing Serializable have simply been dropped and left out of the serialized representation. To define keys with such behavior in this enum, provide a value of false for the reportValueNotSerializable property. When migrating existing properties to this enum, one may wish to consider using this by default, to preserve backward compatibility.

To instead have a NotSerializableException thrown when a non-Serializable property is encountered, provide the value of true for the reportValueNotSerializable property. This is useful when the property represents something that the developer needs to know about when it cannot be serialized.