com.google.appengine.api.datastore.Key can not be found in source packages?!

[Eric Atkinson]

I get the follwing compile error -- com.google.appengine.api.datastore.Key can not be found in source packages. Check the inheritance chain from your module; it may not be inheriting a required module or a module may not be adding its source path entries properly -- with the below code snippet.

What's wrong with this code? Why can't the compiler see com.google.appengine.api.datastore.Key. I assume by "inheritance chain" it means the build path and that includes com.google.appengine.api.datastore.Key in the app eng SDK, so why am I getting the above compile error in the following code:

package com.sis.app.shared;

import javax.jdo.annotations.PersistenceCapable;

import javax.jdo.annotations.Persistent;

import javax.jdo.annotations.IdGeneratorStrategy;

import javax.jdo.annotations.PrimaryKey;

import com.google.appengine.api.datastore.Key;

@SuppressWarnings("serial")

@PersistenceCapable

public class ModelMember implements Serializable {

    @PrimaryKey

    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)

    private Key key;

[Eric Atkinson]

This answer to this -- in the Eclispe IDE -- is to uncheck "build automatically" and then hit "build all", and then it can see it. Strange, but true.