--- old/src/share/vm/jfr/dcmd/jfrDcmds.cpp	2019-09-27 13:25:58.697533497 +0800
+++ new/src/share/vm/jfr/dcmd/jfrDcmds.cpp	2019-09-27 13:25:58.596529939 +0800
@@ -434,7 +434,13 @@
 
   jobjectArray settings = NULL;
   if (_settings.is_set()) {
-    const int length = _settings.value()->array()->length();
+    int length = _settings.value()->array()->length();
+    if (length == 1) {
+      const char* c_str = _settings.value()->array()->at(0);
+      if (strcmp(c_str, "none") == 0) {
+        length = 0;
+      }
+    }
     settings = JfrJavaSupport::new_string_array(length, CHECK);
     assert(settings != NULL, "invariant");
     for (int i = 0; i < length; ++i) {