Unnatural bugs

Example 1: Wrong initialization value bug

  if (isTerminated()) {
    // Before (entropy = 5.96485):
-   terminationFuture.@\Red{setSuccess}@(null);
    // After (entropy = 1.33915):
+   terminationFuture.@\dkgreen{trySuccess}@(null);
   }

Example 2: Wrong method call bug

  if (newState.isClosed()) {
    // Before (entropy = 6.07042):
-   this.tokenInfo = @\Red{null}@;
    // After (entropy = 1.95014):
+   this.tokenInfo = @\dkgreen{AccessToken.createEmptyToken}@
                       @\dkgreen{(Collections.emptyList())}@;
  }
  ...

Example 3: Unhandled exception bug

  if (!directory.exists())
    // Before (entropy = 9.213675):
-   @\Red{directory.mkdir();}@
    // After (entropy = 5.33941):
+   @\dkgreen{if (!directory.mkdir())}@
+     @\dkgreen{throw new IOException}@
           @\dkgreen{("Cannot create directory: " + directory)}@;

...

Natural bugs

Example 1: NBF could not detect the bug as entropy increased after the fix

if (maxHeaderSize <= 0) {
   throw new IllegalArgumentException(
     // Before (entropy = 2.696275):
-    "maxHeaderSize must be a positive integer: "
                          + @\Red{maxChunkSize)}@;
     // After (entropy = 8.447305):
+    "maxHeaderSize must be a positive integer: "
                          + @\dkgreen{maxHeaderSize)}@;
}

Example 2: NBF detected this line incorrectly as buggy due to high entropy value

   // Entropy = 9.892635
   Logger logger = new Logger(LoggingBehaviors.REQUESTS, "Request");
    ...