Make CoreSession.save/createDocument raise helpful ClientExceptions instead of NullPointerExceptions

The following change will help "customers" of the CoreSession API to better spot the origin of their mistake when using the CoreSession methods with invalid argument:

Index: nuxeo-core/src/main/java/org/nuxeo/ecm/core/api/DocumentResolver.java
===================================================================
— nuxeo-core/src/main/java/org/nuxeo/ecm/core/api/DocumentResolver.java (revision 29620)
+++ nuxeo-core/src/main/java/org/nuxeo/ecm/core/api/DocumentResolver.java (working copy)
@@ -54,6 +54,9 @@
*/
public static Document resolveReference(Session session, DocumentRef docRef)
throws DocumentException {
+ if (docRef == null)

{ + throw new DocumentException("Invalid reference (null)"); + }

int type = docRef.type();
Object ref = docRef.reference();
if (ref == null) {
Index: nuxeo-core/src/main/java/org/nuxeo/ecm/core/api/AbstractSession.java
===================================================================
— nuxeo-core/src/main/java/org/nuxeo/ecm/core/api/AbstractSession.java (revision 29620)
+++ nuxeo-core/src/main/java/org/nuxeo/ecm/core/api/AbstractSession.java (working copy)
@@ -39,7 +39,6 @@
import org.nuxeo.common.collections.ScopedMap;
import org.nuxeo.common.utils.IdUtils;
import org.nuxeo.common.utils.Path;
-import org.nuxeo.common.utils.StringUtils;
import org.nuxeo.ecm.core.NXCore;
import org.nuxeo.ecm.core.api.event.CoreEvent;
import org.nuxeo.ecm.core.api.event.CoreEventConstants;
@@ -593,8 +592,18 @@
String name = docModel.getName();
String typeName = docModel.getType();
DocumentRef parentRef = docModel.getParentRef();

• assert typeName != null;
• assert parentRef != null;
  + if (typeName == null) { + throw new ClientException( + String.format( + "cannot create document '%s' with undefined type name", + docModel.getTitle())); + }

  + if (parentRef == null)

  { + throw new ClientException( + String.format( + "cannot create document '%s' with undefined reference to parent document", + docModel.getTitle())); + }

  try {
  Document folder = resolveReference(parentRef);
  checkPermission(folder, ADD_CHILDREN);
  @@ -1304,6 +1313,14 @@
  public DocumentModel saveDocument(DocumentModel docModel)
  throws ClientException {
  try {
  + if (docModel.getRef() == null)

  { + throw new ClientException(String.format( + "cannot save document '%s' with null reference: " + + "document has probably not yet been created " + + "in the repository with " + + "'CoreSession.createDocument(docModel)'", + docModel.getTitle())); + }

  Document doc = resolveReference(docModel.getRef());
  checkPermission(doc, WRITE);