cdm/src/main/java/ucar/util/prefs/PreferencesExt.java
public void putBeanCollection(String key, Collection newValue) {
      // if matches a stored Default, dont store
      Object oldValue = getBean(key, null);
      if ((oldValue == null) || !oldValue.equals( newValue))
        keyValues.put( key, new Bean.Collection(newValue));
    }
public void putBeanCollection(String key, Collection newValue) {
      // if matches a stored Default, dont store
      Object oldValue = getBean(key, null);
      if ((oldValue == null) || !oldValue.equals( newValue))
        keyValues.put( key, new Bean.Collection(newValue));
    }
Stores a Collection of beans. The beans are stored using simple bean properties.
The collection of beans must all be of the same class.

@param key key with which the specified collection is to be associated.
@param newValue store this collection of beans.
@throws NullPointerException if key or value is <tt>null</tt>.
@throws IllegalStateException if this node (or an ancestor) has been
removed with the {@link #removeNode()} method.