src/jdk.compiler/share/classes/com/sun/tools/javac/file/BaseFileManager.java

@@ -272,10 +272,11 @@
          Option o = Option.lookup(option, javacFileManagerOptions);
          return (o == null) ? -1 : o.hasArg() ? 1 : 0;
      }
  
      protected String multiReleaseValue;
+     protected boolean previewMode;
  
      /**
       * Common back end for OptionHelper handleFileManagerOption.
       * @param option the option whose value to be set
       * @param value the value for the option

@@ -290,10 +291,15 @@
              case MULTIRELEASE:
                  multiReleaseValue = value;
                  locations.setMultiReleaseValue(value);
                  return true;
  
+             case PREVIEWMODE:
+                 previewMode = Boolean.parseBoolean(value);
+                 locations.setPreviewMode(previewMode);
+                 return true;
+ 
              default:
                  return locations.handleOption(option, value);
          }
      }