Remove duplicate classpath (#223)

* Remove duplicate classpath.

* use LinkedHashSet to check duplicate and keep the order.

Author: andxu

com.microsoft.java.debug.plugin/src/main/java/com/microsoft/java/debug/plugin/internal/ResolveClasspathsHandler.java

@@ -12,7 +12,9 @@
 package com.microsoft.java.debug.plugin.internal;
 
 import java.util.ArrayList;
+import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Set;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import java.util.stream.Collectors;
@@ -177,7 +179,7 @@ private static String[][] computeClassPath(IJavaProject javaProject) throws Core
 
     private static String[] computeDefaultRuntimeClassPath(IJavaProject jproject) throws CoreException {
         IRuntimeClasspathEntry[] unresolved = JavaRuntime.computeUnresolvedRuntimeClasspath(jproject);
-        List<String> resolved = new ArrayList<>(unresolved.length);
+        Set<String> resolved = new LinkedHashSet<String>();
         for (int i = 0; i < unresolved.length; i++) {
             IRuntimeClasspathEntry entry = unresolved[i];
             if (entry.getClasspathProperty() == IRuntimeClasspathEntry.USER_CLASSES) {
@@ -189,6 +191,7 @@ private static String[] computeDefaultRuntimeClassPath(IJavaProject jproject) th
                     }
                     String location = entries[j].getLocation();
                     if (location != null) {
+                        // remove duplicate classpath
                         resolved.add(location);
                     }
                 }