OLINGO-650: supporting the complex properties in expand context url generation

lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/utils/ContextURLHelper.java

@@ -29,6 +29,8 @@ import org.apache.olingo.commons.api.edm.EdmStructuredType;
 import org.apache.olingo.commons.core.Encoder;
 import org.apache.olingo.server.api.serializer.SerializerException;
 import org.apache.olingo.server.api.uri.UriParameter;
+import org.apache.olingo.server.api.uri.UriResource;
+import org.apache.olingo.server.api.uri.UriResourceProperty;
 import org.apache.olingo.server.api.uri.queryoption.ExpandItem;
 import org.apache.olingo.server.api.uri.queryoption.ExpandOption;
 import org.apache.olingo.server.api.uri.queryoption.SelectItem;
@@ -117,11 +119,39 @@ public final class ContextURLHelper {
             }
             result.append(Encoder.encode(propertyName)).append('(').append(innerSelectList).append(')');
           }
+        } else {
+          final List<UriResource> resourceParts = expandItem.getResourcePath().getUriResourceParts();
+          if(resourceParts.size() > 1) {
+            if (result.length() > 0) {
+              result.append(',');
+            }            
+            final List<String> path = getPropertyPath(resourceParts);
+            String propertyPath = buildPropertyPath(path);            
+            result.append(Encoder.encode(propertyName));
+            result.append("/").append(propertyPath);
+          }
         }
       }
     }
   }
 
+  private static List<String> getPropertyPath(final List<UriResource> path) {
+    List<String> result = new LinkedList<String>();
+    int index = 1;
+    while (index < path.size() && path.get(index) instanceof UriResourceProperty) {
+      result.add(((UriResourceProperty) path.get(index)).getProperty().getName());
+      index++;
+    }
+    return result;
+  }
+
+  private static String buildPropertyPath(final List<String> path) {
+    StringBuilder result = new StringBuilder();
+    for (final String segment : path) {
+      result.append(result.length() == 0 ? "" : '/').append(Encoder.encode(segment)); //$NON-NLS-1$
+    }
+    return result.length() == 0?null:result.toString();
+  }  
   private static List<List<String>> getComplexSelectedPaths(final EdmProperty edmProperty,
       final Set<List<String>> selectedPaths) {
     List<List<String>> result = new ArrayList<List<String>>();

lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/utils/ExpandSelectHelper.java

@@ -127,15 +127,10 @@ public abstract class ExpandSelectHelper {
     Set<String> expanded = new HashSet<String>();
     for (final ExpandItem item : expandItems) {
       final List<UriResource> resourceParts = item.getResourcePath().getUriResourceParts();
-      if (resourceParts.size() == 1) {
       final UriResource resource = resourceParts.get(0);
       if (resource instanceof UriResourceNavigation) {
         expanded.add(((UriResourceNavigation) resource).getProperty().getName());
       }
-      } else {
-        throw new SerializerException("Expand is not supported within complex properties.",
-            SerializerException.MessageKeys.NOT_IMPLEMENTED);
-      }
     }
     return expanded;
   }

lib/server-test/src/test/java/org/apache/olingo/server/core/serializer/utils/ContextURLHelperTest.java

@@ -116,6 +116,22 @@ public class ContextURLHelperTest {
     assertEquals("$metadata#ESTwoPrim", ContextURLBuilder.create(contextURL).toASCIIString());
   }
 
+  @Test
+  public void buildExpandWithNavigationProperty() throws Exception {
+    final EdmEntitySet entitySet = entityContainer.getEntitySet("ESTwoPrim");
+    final ExpandOption expand = ExpandSelectMock.mockExpandOption(Arrays.asList(
+        ExpandSelectMock.mockExpandItem(entitySet, "NavPropertyETAllPrimOne", "PropertyString")));
+    final SelectItem selectItem1 = ExpandSelectMock.mockSelectItem(entitySet, "PropertyInt16");
+    final SelectOption select = ExpandSelectMock.mockSelectOption(Arrays.asList(
+        selectItem1));
+    
+    final ContextURL contextURL = ContextURL.with().entitySet(entitySet)
+        .selectList(ContextURLHelper.buildSelectList(entitySet.getEntityType(), expand, select)).build();
+    assertEquals("$metadata#ESTwoPrim(PropertyInt16,NavPropertyETAllPrimOne/PropertyString)", 
+        ContextURLBuilder.create(contextURL).toASCIIString());
+  }
+
+  
   @Test
   public void buildExpandSelect() throws Exception {
     final EdmEntitySet entitySet = entityContainer.getEntitySet("ESTwoPrim");