Fix class file version detection

we are forcing 1.8 class file version when it's below, but we
are checking against the full version while we need to check against
the major version only

Author: jpbempel

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/agent/DebuggerTransformer.java

@@ -422,7 +422,7 @@ private byte[] writeClassFile(
       ClassLoader loader,
       String classFilePath,
       ClassNode classNode) {
-    if (classNode.version < Opcodes.V1_8) {
+    if ((classNode.version & 0xFF) < Opcodes.V1_8) {
       // Class file version must be at least 1.8 (52)
       classNode.version = Opcodes.V1_8;
     }

dd-java-agent/agent-debugger/src/test/java/com/datadog/debugger/agent/CapturedSnapshotTest.java

@@ -66,6 +66,7 @@
 import java.lang.reflect.Modifier;
 import java.net.URISyntaxException;
 import java.net.URL;
+import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -211,6 +212,24 @@ public void veryOldClassFile() throws Exception {
     assertOneSnapshot(listener);
   }
 
+  @Test
+  public void oldClass1_1() throws Exception {
+    final String CLASS_NAME = "org.apache.commons.lang.BooleanUtils"; // compiled with jdk 1.1
+    TestSnapshotListener listener = installSingleProbe(CLASS_NAME, "toBoolean", null);
+    when(config.isDebuggerVerifyByteCode()).thenReturn(true);
+    Class<?> testClass =
+        loadClass(
+            CLASS_NAME,
+            Paths.get(
+                    CapturedSnapshotTest.class
+                        .getResource("/classfiles/BooleanUtils.classfile")
+                        .toURI())
+                .toString());
+    boolean result = Reflect.onClass(testClass).call("toBoolean", Boolean.TRUE).get();
+    assertTrue(result);
+    assertOneSnapshot(listener);
+  }
+
   @Test
   public void oldJavacBug() throws Exception {
     final String CLASS_NAME = "com.datadog.debugger.classfiles.JavacBug"; // compiled with jdk 1.6