XDGF: fix the fix

- Use Collections.emptySet() for an iterator instead
- Bump curvesapi to 1.03, which is compiled for JDK 1.5

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1709463 13f79535-47bb-0310-9956-ffa450edef68

build.xml

@@ -177,9 +177,9 @@ under the License.
     <property name="dsig.sl4j-api.url" value="${repository.m2}/maven2/org/slf4j/slf4j-api/1.7.7/slf4j-api-1.7.7.jar"/>
 
     <!-- jars in the lib-ooxml directory, see the fetch-ooxml-jars target-->
-    <property name="ooxml.curvesapi.jar" location="${ooxml.lib}/curvesapi-1.02.jar"/>
+    <property name="ooxml.curvesapi.jar" location="${ooxml.lib}/curvesapi-1.03.jar"/>
     <property name="ooxml.curvesapi.url"
-              value="${repository.m2}/maven2/com/github/virtuald/curvesapi/1.02/curvesapi-1.02.jar"/>
+              value="${repository.m2}/maven2/com/github/virtuald/curvesapi/1.03/curvesapi-1.03.jar"/>
     <property name="ooxml.xmlbeans23.jar" location="${ooxml.lib}/xmlbeans-2.3.0.jar"/>
     <property name="ooxml.xmlbeans23.url"
               value="${repository.m2}/maven2/org/apache/xmlbeans/xmlbeans/2.3.0/xmlbeans-2.3.0.jar"/>

maven/poi-ooxml.pom

@@ -72,7 +72,7 @@
     <dependency>
     	<groupId>com.github.virtuald</groupId>
     	<artifactId>curvesapi</artifactId>
-    	<version>1.02</version>
+    	<version>1.03</version>
     </dependency>
   </dependencies>
 </project>

src/ooxml/java/org/apache/poi/xdgf/usermodel/section/CombinedIterable.java

@@ -17,9 +17,11 @@
 
 package org.apache.poi.xdgf.usermodel.section;
 
+import java.util.Collections;
 import java.util.Iterator;
 import java.util.Map.Entry;
 import java.util.NoSuchElementException;
+import java.util.Set;
 import java.util.SortedMap;
 
 /**
@@ -31,25 +33,6 @@ public class CombinedIterable<T> implements Iterable<T> {
 
     final SortedMap<Long, T> _baseItems;
     final SortedMap<Long, T> _masterItems;
-    
-    private static final class EmptyIterator<T> implements Iterator<T> {
-
-        @Override
-        public boolean hasNext() {
-            return false;
-        }
-
-        @Override
-        public T next() {
-            return null;
-        }
-        
-        @Override
-        public void remove() {
-            throw new UnsupportedOperationException();
-        }
-        
-    }
 
     public CombinedIterable(SortedMap<Long, T> baseItems,
             SortedMap<Long, T> masterItems) {
@@ -62,10 +45,12 @@ public class CombinedIterable<T> implements Iterable<T> {
 
         final Iterator<Entry<Long, T>> vmasterI;
 
-        if (_masterItems != null)
+        if (_masterItems != null) {
             vmasterI = _masterItems.entrySet().iterator();
-        else
-            vmasterI = new EmptyIterator<Entry<Long, T>>();
+        } else {
+            final Set<Entry<Long, T>> empty = Collections.emptySet();
+            vmasterI = empty.iterator();
+        }
 
         return new Iterator<T>() {