Fix join helper for arrays of primitives

handlebars/src/main/java/com/github/jknack/handlebars/helper/StringHelpers.java

@@ -10,6 +10,7 @@
 import static org.apache.commons.lang3.Validate.validIndex;
 
 import java.io.IOException;
+import java.lang.reflect.Array;
 import java.math.RoundingMode;
 import java.text.DecimalFormat;
 import java.text.DecimalFormatSymbols;
@@ -170,7 +171,13 @@ protected CharSequence safeApply(final Object context, final Options options) {
         return prefix + StringUtils.join((Iterator) context, (String) separator) + suffix;
       }
       if (context.getClass().isArray()) {
-        return prefix + StringUtils.join((Object[]) context, (String) separator) + suffix;
+        // arrays of primitives (int[], long[], ...) cannot be cast to Object[]
+        int length = Array.getLength(context);
+        Object[] items = new Object[length];
+        for (int i = 0; i < length; i++) {
+          items[i] = Array.get(context, i);
+        }
+        return prefix + StringUtils.join(items, (String) separator) + suffix;
       }
       // join everything as single values
       Object[] values = new Object[options.params.length];

handlebars/src/test/java/com/github/jknack/handlebars/helper/StringHelpersTest.java

@@ -168,6 +168,12 @@ public void joinArray() throws IOException {
         "6, 7, 8");
   }
 
+  @Test
+  public void joinPrimitiveArray() throws IOException {
+    shouldCompileTo(
+        "{{{join this \", \"}}}", new int[] {6, 7, 8}, $("join", StringHelpers.join), "6, 7, 8");
+  }
+
   @Test
   public void joinValues() throws IOException {
     shouldCompileTo(