[ZEPPELIN-2403] converter for old settings to new (with widgets)

docs/install/upgrade.md

@@ -61,7 +61,7 @@ So, copying `notebook` and `conf` directory should be enough.
 
  - From 0.8, we recommend to use `PYSPARK_PYTHON` and `PYSPARK_DRIVER_PYTHON` instead of `zeppelin.pyspark.python` as `zeppelin.pyspark.python` only effects driver. You can use `PYSPARK_PYTHON` and `PYSPARK_DRIVER_PYTHON` as using them in spark.
  - From 0.8, depending on your device, the keyboard shortcut `Ctrl-L` or `Command-L` which goes to the line somewhere user wants is not supported. 
- - From 0.8, changed the format settings for interpreters (`interpreter.json`)
+ - From 0.8, changed the format settings for interpreters (`interpreter.json`). Old settings automatically converted to widget `textarea` and type `string`.
  
    old format:
    ```

zeppelin-zengine/src/main/java/org/apache/zeppelin/interpreter/InterpreterSetting.java

@@ -29,6 +29,8 @@ import java.util.Set;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 
 import com.google.gson.annotations.SerializedName;
+import com.google.gson.internal.StringMap;
+
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -410,4 +412,29 @@ public class InterpreterSetting {
   public void clearNoteIdAndParaMap() {
     runtimeInfosToBeCleared = null;
   }
+
+  // For backward compatibility of interpreter.json format after ZEPPELIN-2403
+  public void convertFlatPropertiesToPropertiesWithWidgets() {
+    StringMap newProperties = new StringMap();
+    if (properties != null && properties instanceof StringMap) {
+      StringMap p = (StringMap) properties;
+
+      for (Object o : p.entrySet()) {
+        Map.Entry entry = (Map.Entry) o;
+        if (!(entry.getValue() instanceof StringMap)) {
+          StringMap newProperty = new StringMap();
+          newProperty.put("name", entry.getKey());
+          newProperty.put("value", entry.getValue());
+          newProperty.put("widget", InterpreterPropertyWidget.TEXTAREA.getValue());
+          newProperty.put("type", InterpreterPropertyType.STRING.getValue());
+          newProperties.put(entry.getKey().toString(), newProperty);
+        } else {
+          // already converted
+          return;
+        }
+      }
+
+      this.properties = newProperties;
+    }
+  }
 }

zeppelin-zengine/src/main/java/org/apache/zeppelin/interpreter/InterpreterSettingManager.java

@@ -165,6 +165,9 @@ public class InterpreterSettingManager {
 
       for (String k : infoSaving.interpreterSettings.keySet()) {
         InterpreterSetting setting = infoSaving.interpreterSettings.get(k);
+
+        setting.convertFlatPropertiesToPropertiesWithWidgets();
+
         List<InterpreterInfo> infos = setting.getInterpreterInfos();
 
         // Convert json StringMap to Properties