Fix issue with ByteBuffer when compiling on Java 9+ (#9)

Java 9+ has ABI breakage on ByteBuffer's clear method, which then causes an error for anyone attempting to run the plugin on Java 8. This change addresses that by changing the way the buffer is read in, avoiding that method call entirely.

src/main/java/com/wimbli/WorldBorder/WorldFileData.java

@@ -192,20 +192,11 @@ private List<Boolean> getRegionData(CoordXZ region)
 			if ( ! coord.equals(region))
 				continue;
 
-			try
+			try (final RandomAccessFile regionData = new RandomAccessFile(this.regionFile(i), "r"))
 			{
-				RandomAccessFile regionData = new RandomAccessFile(this.regionFile(i), "r");
-
-				// Use of ByteBuffer+IntBuffer for reading file headers to improve performance, as suggested by aikar, reference:
-				// https://github.com/PaperMC/Paper/blob/b62dfa0bf95ac27ba0fbb3fae18c064e4bb61d50/Spigot-Server-Patches/0086-Reduce-IO-ops-opening-a-new-region-file.patch
-				ByteBuffer header = ByteBuffer.allocate(8192);
-				while (header.hasRemaining()) 
-				{
-					if (regionData.getChannel().read(header) == -1)
-						throw new EOFException();
-				}
-				header.clear();
-				IntBuffer headerAsInts = header.asIntBuffer();
+				final byte[] header = new byte[8192];
+ 				regionData.readFully(header);
+				IntBuffer headerAsInts = ByteBuffer.wrap(header).asIntBuffer();
 
 				// first 4096 bytes of region file consists of 4-byte int pointers to chunk data in the file (32*32 chunks = 1024; 1024 chunks * 4 bytes each = 4096)
 				for (int j = 0; j < 1024; j++)
@@ -221,7 +212,6 @@ private List<Boolean> getRegionData(CoordXZ region)
 					if ((headerAsInts.get() == 0) && data.get(j))
 						data.set(j, false);
 				}
-				regionData.close();
 			}
 			catch (FileNotFoundException ex)
 			{