Fix javadoc for module "json" (#396)

Also simplifies a constructor.

Author: dr0i

metafacture-json/src/main/java/org/metafacture/json/JsonDecoder.java

@@ -60,20 +60,14 @@ public final class JsonDecoder extends DefaultObjectPipe<String, StreamReceiver>
     private final JsonFactory jsonFactory = new JsonFactory();
 
     private JsonParser jsonParser;
-    private String arrayMarker;
-    private String arrayName;
-    private String recordId;
-    private int recordCount;
+    private String arrayMarker = DEFAULT_ARRAY_MARKER;
+    private String arrayName = DEFAULT_ARRAY_NAME;
+    private String recordId = DEFAULT_RECORD_ID;
+    private String recordPath = DEFAULT_ROOT_PATH;
 
-    private String recordPath;
+    private int recordCount;
 
     public JsonDecoder() {
-        setArrayMarker(DEFAULT_ARRAY_MARKER);
-        setArrayName(DEFAULT_ARRAY_NAME);
-        setRecordId(DEFAULT_RECORD_ID);
-        setRecordPath(DEFAULT_ROOT_PATH);
-
-        resetRecordCount();
     }
 
     public void setAllowComments(final boolean allowComments) {

metafacture-json/src/main/java/org/metafacture/json/JsonEncoder.java

@@ -62,6 +62,10 @@ public final class JsonEncoder extends DefaultStreamPipe<ObjectReceiver<String>>
 
     private String arrayMarker = ARRAY_MARKER;
 
+    /**
+     * Default constructor initializes the JsonGenerator. The root value separator
+     * of the JsonGenerator is set to null.
+     */
     public JsonEncoder() {
         try {
             jsonGenerator = new JsonFactory().createGenerator(writer);