Remove bogus @Nullable annotation from DataInputStream.read. (#69)

I suspect that this was just an accident from the large initial commit
of Checker Framework annotations:
https://github.com/typetools/jdk/blame/f4d40f209b5b6e229199a6c134b105d54d9241dd/src/java.base/share/classes/java/io/DataInputStream.java#L113

src/java.base/share/classes/java/io/DataInputStream.java

@@ -113,7 +113,7 @@ public DataInputStream(InputStream in) {
      * @see        java.io.FilterInputStream#in
      * @see        java.io.InputStream#read(byte[], int, int)
      */
-    public final int read(byte @Nullable [] b) throws IOException {
+    public final int read(byte[] b) throws IOException {
         return in.read(b, 0, b.length);
     }