Add doc

java/org/rocksdb/Options.java

@@ -216,7 +216,8 @@ public class Options {
 
   /*
    * Pointer to statistics object. Should only be called after statistics has
-   * been created by createStatistics() call.
+   * been created by createStatistics() call. Calls createStatistics() if
+   * C++ returns NULL pointer for statistics.
    *
    * @see createStatistics()
    */

java/rocksjni/statistics.cc

@@ -28,6 +28,11 @@ jlong Java_org_rocksdb_Statistics_getTickerCount0(
   return st->getTickerCount(static_cast<rocksdb::Tickers>(tickerType));
 }
 
+/*
+ * Class:     org_rocksdb_Statistics
+ * Method:    geHistogramData0
+ * Signature: (IJ)Lorg/rocksdb/HistogramData;
+ */
 jobject Java_org_rocksdb_Statistics_geHistogramData0(
   JNIEnv* env, jobject jobj, int histogramType, jlong handle) {
   auto st = reinterpret_cast<rocksdb::Statistics*>(handle);