The JSR-10 Expert Group recommends the following changes to the Preferences API (and implementation):

Add a new (Throwable) constructor to BackingStoreException, as it will
typically be a "chained exception."

Modify AbstractPreferences.removeNodeSpi() to throw
BackingStoreException. This is a no-brainer given that removeNode throws
the same exception.

Modify AbstractPreferences.removeNode to use childrenNamesSpi
Spec for MAX_XXX_LENGTH said bytes when it meant characters.

Remove newNode param from AbstractPreferences constructor. Replace it
with protected field, which subclass constructor is obligated to set
if appropriate.

Rename children method to childrenNames and change its behavior to
return an array containing the names of this nodes children instead of the
nodes themselves. This improves performance.

DTD for exported form: modify root and node to *require* a map, and
modify map to contain entry* instead of entry+. This is cleaner, and
results in much cleaner XmlSupport code. Also modify preferences to
*require* a root.

Change name of node conventionally associated with programs in the
unnamed package from "<temporary>" to "<unnamed>".

Replace "lineNumber" support in InvalidPreferencesFormatException with
nested exception ("cause") support.

If getSpi(String) throws an exception, it should be caught, and the default
value returned from get(String).

Describe the correct exception behavior of the SPI calls in AbstractPreferences.

Provide additional information about implementor responsibilities.

Describe locking behavior of isRemoved.

Modify sync spec to allow call on removed node.