mapping.setAttributeElementClass(double[].class);

XMLCompositeDirectCollectionMapping valueMapping = new XMLCompositeDirectCollectionMapping();
ArrayAttributeAccessor<String> arrayAttributeAccessor = new ArrayAttributeAccessor<String>(String.class);
arrayAttributeAccessor.setAttributeName("value");
valueMapping.setAttributeAccessor(arrayAttributeAccessor);
valueMapping.setXPath("valuePartB/text()");
xmlDescriptor.addMapping(valueMapping);

import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Vector;

import org.eclipse.persistence.exceptions.DescriptorException;
import org.eclipse.persistence.internal.descriptors.InstanceVariableAttributeAccessor;

public class ArrayAttributeAccessor<T> extends InstanceVariableAttributeAccessor {

    private Class<T> itemType;
    
    public ArrayAttributeAccessor(Class<T> itemType) {
        this.itemType = itemType;
    }
    
    @Override
    public Object getAttributeValueFromObject(Object object) throws DescriptorException {
        T[] array = (T[]) super.getAttributeValueFromObject(object);
        Vector<T> vector = new Vector<T>(array.length);
        for(T t : array) {
            vector.add(t);
        }
        return vector;
    }

    @Override
    public void setAttributeValueInObject(Object object, Object value) throws DescriptorException {
        Vector<T> vector = (Vector<T>) value;
        T[] array = (T[]) Array.newInstance(itemType, vector.size());
        vector.toArray(array);
        super.setAttributeValueInObject(object, array);
    }

}