Removed XZ compression feature of serialized IValues

pom.xml

@@ -153,11 +153,6 @@
 		<artifactId>capsule</artifactId>
 			<version>0.7.1</version>
 		</dependency>
-		<dependency>
-			<groupId>org.tukaani</groupId>
-			<artifactId>xz</artifactId>
-			<version>1.9</version>
-		</dependency>
 		<dependency>
 			<groupId>com.github.luben</groupId>
 			<artifactId>zstd-jni</artifactId>

src/main/java/io/usethesource/vallang/io/binary/stream/Compressor.java

@@ -27,9 +27,6 @@
 import java.io.OutputStream;
 import java.util.zip.GZIPInputStream;
 import java.util.zip.GZIPOutputStream;
-import org.tukaani.xz.LZMA2Options;
-import org.tukaani.xz.XZInputStream;
-import org.tukaani.xz.XZOutputStream;
 import com.github.luben.zstd.ZstdInputStream;
 import com.github.luben.zstd.ZstdOutputStream;
 import com.github.luben.zstd.util.Native;
@@ -60,8 +57,8 @@ public void setLevel(int level) {
                 result.setLevel(level);
                 return result;
             }
-            case Header.Compression.XZ: {
-                return new XZOutputStream(rawStream, new LZMA2Options(level));
+            case Header.Compression.UNSUPPORTED_XZ: {
+                throw new UnsupportedOperationException("XZ compression is not supported anymore, please use an older version of rascal/vallang to open the file and store it with a different level of compression");
             }
             case Header.Compression.ZSTD: {
                 return new ZstdOutputStream(rawStream, level);
@@ -77,8 +74,8 @@ public static InputStream wrapStream(InputStream raw, int algorithm) throws IOEx
                 return raw;
             case Header.Compression.GZIP:
                 return new GZIPInputStream(raw);
-            case Header.Compression.XZ:
-                return new XZInputStream(raw);
+            case Header.Compression.UNSUPPORTED_XZ:
+                throw new UnsupportedOperationException("XZ compression is not supported anymore, please use an older version of rascal/vallang to open the file and store it with a different level of compression");
             case Header.Compression.ZSTD:
                 if (Compressor.zstdAvailable()) {
                     if (raw instanceof ByteBufferInputStream && ((ByteBufferInputStream)raw).getByteBuffer().isDirect()) {

src/main/java/io/usethesource/vallang/io/binary/stream/Header.java

@@ -17,7 +17,8 @@
     public static final class Compression {
         public static final byte NONE = 0;
         public static final byte GZIP = 1;
-        public static final byte XZ = 2;
+        /** Never officially available, but still reserved */
+        public static final byte UNSUPPORTED_XZ = 2;
         public static final byte ZSTD = 3;
     }
 

src/main/java/io/usethesource/vallang/io/binary/stream/IValueInputStream.java

@@ -16,6 +16,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.channels.FileChannel;
+import java.util.Arrays;
 import java.util.function.Supplier;
 
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -49,13 +50,25 @@ public IValueInputStream(InputStream in, IValueFactory vf, Supplier<TypeStore> t
         while (read < currentHeader.length) {
             read += in.read(currentHeader, read, currentHeader.length - read);
         }
+        if (!Arrays.equals(currentHeader, Header.MAIN)) {
+            throw new IOException("Incorrect file header, expected: [" + toHex(Header.MAIN) + "] but found: [" + toHex(currentHeader) + "]");
+        }
 
         int compression = in.read();
         in = Compressor.wrapStream(in, compression);
         reader = new BinaryWireInputStream(in);
     }
 
 
+    private static String toHex(byte[] main) {
+        String result = "";
+        for (byte b : main) {
+            result += String.format("%#04x ", b);
+        }
+        return result.trim();
+    }
+
+
     public IValueInputStream(FileChannel channel, IValueFactory vf, Supplier<TypeStore> typeStoreSupplier) throws IOException {
         this(new FileChannelDirectInputStream(channel), vf, typeStoreSupplier);
     }

src/main/java/io/usethesource/vallang/io/binary/stream/IValueOutputStream.java

@@ -55,7 +55,7 @@ public enum CompressionRate {
         Light(Header.Compression.ZSTD, 1),
         Normal(Header.Compression.ZSTD, 5),
         Strong(Header.Compression.ZSTD, 13),
-        Extreme(Header.Compression.XZ, 6),
+        Extreme(Header.Compression.ZSTD, 19),
         XML(Compression.NONE, 0)
         ;