diff --git a/Clipper/pom.xml b/Clipper/pom.xml
new file mode 100644
index 0000000..0571dd7
--- /dev/null
+++ b/Clipper/pom.xml
@@ -0,0 +1,25 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<groupId>Clipper</groupId>
+	<artifactId>Clipper</artifactId>
+	<version>6.2.1</version>
+
+	<properties>
+		<project.build.sourceEncoding>ISO-8859-1</project.build.sourceEncoding>
+	</properties>
+
+	<build>
+		<sourceDirectory>src</sourceDirectory>
+		<plugins>
+			<plugin>
+				<artifactId>maven-compiler-plugin</artifactId>
+				<version>3.1</version>
+				<configuration>
+					<source>1.7</source>
+					<target>1.7</target>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+</project>
\ No newline at end of file
diff --git a/Clipper/src/de/lighti/clipper/ClipperOffset.java b/Clipper/src/de/lighti/clipper/ClipperOffset.java
index 4b333d4..a6d9ce7 100644
--- a/Clipper/src/de/lighti/clipper/ClipperOffset.java
+++ b/Clipper/src/de/lighti/clipper/ClipperOffset.java
@@ -389,7 +389,7 @@ public void execute( PolyTree solution, double delta ) {
             //remove the outer PolyNode rectangle ...
             if (solution.getChildCount() == 1 && solution.getChilds().get( 0 ).getChildCount() > 0) {
                 final PolyNode outerNode = solution.getChilds().get( 0 );
-                solution.getChilds().set( 0, outerNode.getChilds().get( 0 ) );
+                solution.childs.set( 0, outerNode.getChilds().get( 0 ) );
                 solution.getChilds().get( 0 ).setParent( solution );
                 for (int i = 1; i < outerNode.getChildCount(); i++) {
                     solution.addChild( outerNode.getChilds().get( i ) );
diff --git a/Clipper/src/de/lighti/clipper/DefaultClipper.java b/Clipper/src/de/lighti/clipper/DefaultClipper.java
index dfd4190..06c3f16 100644
--- a/Clipper/src/de/lighti/clipper/DefaultClipper.java
+++ b/Clipper/src/de/lighti/clipper/DefaultClipper.java
@@ -562,16 +562,17 @@ public DefaultClipper( int InitOptions ) //constructor
         activeEdges = null;
         sortedEdges = null;
         intersectList = new ArrayList<IntersectNode>();
-        intersectNodeComparer = ( node1, node2 ) -> {
-            final long i = node2.getPt().getY() - node1.getPt().getY();
-            if (i > 0) {
-                return 1;
-            }
-            else if (i < 0) {
-                return -1;
-            }
-            else {
-                return 0;
+        intersectNodeComparer = new Comparator<DefaultClipper.IntersectNode>() {
+            @Override
+            public int compare(IntersectNode node1, IntersectNode node2) {
+                final long i = node2.getPt().getY() - node1.getPt().getY();
+                if (i > 0) {
+                    return 1;
+                } else if (i < 0) {
+                    return -1;
+                } else {
+                    return 0;
+                }
             }
         };
 
@@ -908,6 +909,9 @@ private void buildResult2( PolyTree polytree ) {
         //add each output polygon/contour to polytree ...
         for (int i = 0; i < polyOuts.size(); i++) {
             final OutRec outRec = polyOuts.get( i );
+            if (outRec.getPoints() == null) {
+                continue;
+            }
             final int cnt = outRec.getPoints().getPointCount();
             if (outRec.isOpen && cnt < 2 || !outRec.isOpen && cnt < 3) {
                 continue;
diff --git a/Clipper/src/de/lighti/clipper/PolyNode.java b/Clipper/src/de/lighti/clipper/PolyNode.java
index fd5f9c4..9eaf25f 100644
--- a/Clipper/src/de/lighti/clipper/PolyNode.java
+++ b/Clipper/src/de/lighti/clipper/PolyNode.java
@@ -8,7 +8,7 @@
 import de.lighti.clipper.Clipper.JoinType;
 import de.lighti.clipper.Point.LongPoint;
 
-class PolyNode {
+public class PolyNode {
     enum NodeType {
         ANY, OPEN, CLOSED
     }
diff --git a/Clipper/src/de/lighti/clipper/PolyTree.java b/Clipper/src/de/lighti/clipper/PolyTree.java
index f785cc0..b0c191b 100644
--- a/Clipper/src/de/lighti/clipper/PolyTree.java
+++ b/Clipper/src/de/lighti/clipper/PolyTree.java
@@ -3,7 +3,7 @@
 import java.util.ArrayList;
 import java.util.List;
 
-class PolyTree extends PolyNode {
+public class PolyTree extends PolyNode {
     private final List<PolyNode> allPolys = new ArrayList<PolyNode>();
 
     public void Clear() {