SeekableInMemoryByteChannel returns incorrect value for EOF

The NIO2 API's SeekableInMemoryByteChannel currently returns 0 when a read requests data either at the end of the data or past the end of the data.

The API for SeekableByteChannel ( http://docs.oracle.com/javase/7/docs/api/java/nio/channels/SeekableByteChannel.html#read(java.nio.ByteBuffer) ) states the return value should be -1 if EOF has been reached. This behavior is confirmed through testing of FileChannelImpl.

Java's sun.nio.cs.StreamDecoder.readBytes() expects this behavior, throwing an IOException if zero bytes are read.

I encountered this issue using GSON to write and then read a json file from a ShrinkWrap archive as part of a unit test. At the end of reading a json file, GSON checks that the EOF has been reached, and at this point a read returns 0 and causes an exception in sun.nio.cs.StreamDecoder.readBytes().

A unit test showing the issue:

    @Test
    public void test() throws IOException {
        JavaArchive homeArchive = ShrinkWrap.create(JavaArchive.class);
        FileSystem vfs = ShrinkWrapFileSystems.newFileSystem(homeArchive);
        Path path = vfs.getPath("out.json");
        try (BufferedWriter writer = Files.newBufferedWriter(path, Charset.forName("UTF-8"))) {
            new GsonBuilder().create().toJson("Test", writer);
        }
        try (BufferedReader reader = Files.newBufferedReader(path, Charset.forName("UTF-8"))) { 
            assertEquals("Test", new GsonBuilder().create().fromJson(reader), String.class));
        }
    }