Internal refactoring

- Remove dead comment
- Reduce vertical whitespace

Author: garydgregory

src/main/java/org/apache/commons/io/filefilter/MagicNumberFileFilter.java

@@ -229,16 +229,7 @@ public MagicNumberFileFilter(final String magicNumber) {
      *         a negative number.
      */
     public MagicNumberFileFilter(final String magicNumber, final long offset) {
-        Objects.requireNonNull(magicNumber, "magicNumber");
-        if (magicNumber.isEmpty()) {
-            throw new IllegalArgumentException("The magic number must contain at least one byte");
-        }
-        if (offset < 0) {
-            throw new IllegalArgumentException("The offset cannot be negative");
-        }
-
-        this.magicNumbers = magicNumber.getBytes(Charset.defaultCharset()); // explicitly uses the platform default charset
-        this.byteOffset = offset;
+        this(magicNumber.getBytes(Charset.defaultCharset()), offset);
     }
 
     /**

src/main/java/org/apache/commons/io/output/LockableFileWriter.java

@@ -149,9 +149,6 @@ public Builder setLockDirectory(final String lockDirectory) {
     /** The extension for the lock file. */
     private static final String LCK = ".lck";
 
-    // Cannot extend ProxyWriter, as requires writer to be
-    // known when super() is called
-
     /**
      * Constructs a new {@link Builder}.
      *
@@ -250,16 +247,13 @@ public LockableFileWriter(final File file, final Charset charset, final boolean
         if (absFile.isDirectory()) {
             throw new IOException("File specified is a directory");
         }
-
         // init lock file
         final File lockDirFile = new File(lockDir != null ? lockDir : FileUtils.getTempDirectoryPath());
         FileUtils.forceMkdir(lockDirFile);
         testLockDir(lockDirFile);
         lockFile = new File(lockDirFile, absFile.getName() + LCK);
-
         // check if locked
         createLock();
-
         // init wrapped writer
         out = initWriter(absFile, charset, append);
     }
@@ -391,7 +385,6 @@ private Writer initWriter(final File file, final Charset charset, final boolean
         final boolean fileExistedAlready = file.exists();
         try {
             return new OutputStreamWriter(new FileOutputStream(file.getAbsolutePath(), append), Charsets.toCharset(charset));
-
         } catch (final IOException | RuntimeException ex) {
             FileUtils.deleteQuietly(lockFile);
             if (!fileExistedAlready) {