Index: trunk/src/org/openstreetmap/josm/data/osm/DataSet.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/DataSet.java	(revision 14168)
+++ trunk/src/org/openstreetmap/josm/data/osm/DataSet.java	(revision 14169)
@@ -134,6 +134,6 @@
 
     private String name;
-    private DownloadPolicy downloadPolicy;
-    private UploadPolicy uploadPolicy;
+    private DownloadPolicy downloadPolicy = DownloadPolicy.NORMAL;
+    private UploadPolicy uploadPolicy = UploadPolicy.NORMAL;
     /** Flag used to know if the dataset should not be editable */
     private final AtomicBoolean isReadOnly = new AtomicBoolean(false);
@@ -329,5 +329,5 @@
     @Override
     public void setDownloadPolicy(DownloadPolicy downloadPolicy) {
-        this.downloadPolicy = downloadPolicy;
+        this.downloadPolicy = Objects.requireNonNull(downloadPolicy);
     }
 
@@ -339,5 +339,5 @@
     @Override
     public void setUploadPolicy(UploadPolicy uploadPolicy) {
-        this.uploadPolicy = uploadPolicy;
+        this.uploadPolicy = Objects.requireNonNull(uploadPolicy);
     }
 
Index: trunk/src/org/openstreetmap/josm/data/osm/OsmData.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/OsmData.java	(revision 14168)
+++ trunk/src/org/openstreetmap/josm/data/osm/OsmData.java	(revision 14169)
@@ -229,5 +229,5 @@
     /**
      * Sets the download policy.
-     * @param downloadPolicy the download policy
+     * @param downloadPolicy the download policy. Must not be null
      * @see #getUploadPolicy()
      * @since 13453
@@ -244,5 +244,5 @@
     /**
      * Sets the upload policy.
-     * @param uploadPolicy the upload policy
+     * @param uploadPolicy the upload policy. Must not be null
      * @see #getUploadPolicy()
      */