Add support of 'auto' value for 'start_offset' transformation parameter (#132)

* Add support of `auto` value for `start_offset` transformation parameter

Author: d-mendoza

cloudinary-core/src/main/java/com/cloudinary/Transformation.java

@@ -589,11 +589,11 @@ public String generate(Map options) {
         String flags = StringUtils.join(ObjectUtils.asArray(options.get("flags")), ".");
 
         String duration = normRangeValue(options.get("duration"));
-        String startOffset = normRangeValue(options.get("start_offset"));
+        String startOffset = normAutoRangeValue(options.get("start_offset"));
         String endOffset = normRangeValue(options.get("end_offset"));
         String[] offset = splitRange(options.get("offset"));
         if (offset != null) {
-            startOffset = normRangeValue(offset[0]);
+            startOffset = normAutoRangeValue(offset[0]);
             endOffset = normRangeValue(offset[1]);
         }
 
@@ -797,6 +797,13 @@ private static String normRangeValue(Object objectValue) {
         return matcher.group(1) + modifier;
     }
 
+    private static String normAutoRangeValue(Object objectValue) {
+        if ("auto".equals(objectValue)) {
+            return objectValue.toString();
+        }
+        return normRangeValue(objectValue);
+    }
+
     private static String processVideoCodecParam(Object param) {
         StringBuilder outParam = new StringBuilder();
         if (param instanceof String) {

cloudinary-core/src/test/java/com/cloudinary/test/CloudinaryTest.java

@@ -728,6 +728,9 @@ public void testStartOffset() {
         actual = cloudinary.url().resourceType("video").transformation(new Transformation().startOffsetPercent(2.63))
                 .generate("video_id");
         assertEquals(VIDEO_UPLOAD_PATH + "so_2.63p/video_id", actual);
+        actual = cloudinary.url().resourceType("video").transformation(new Transformation().startOffset("auto"))
+                .generate("video_id");
+        assertEquals(VIDEO_UPLOAD_PATH + "so_auto/video_id", actual);
     }
 
     @Test