Cleanup nullability annotations

class-inject/src/main/java/datadog/instrument/classinject/package-info.java

@@ -0,0 +1,4 @@
+@ParametersAreNonnullByDefault
+package datadog.instrument.classinject;
+
+import javax.annotation.ParametersAreNonnullByDefault;

class-match/src/main/java/datadog/instrument/classmatch/ClassHeader.java

@@ -6,6 +6,8 @@
 
 package datadog.instrument.classmatch;
 
+import javax.annotation.Nullable;
+
 /** Minimal class header that describes its access modifiers and immediate class hierarchy. */
 public class ClassHeader {
 
@@ -20,13 +22,13 @@ public class ClassHeader {
   /** Internal name of this class. */
   public final String className;
 
-  /** Internal name of the super-class declared by this class. */
-  public final String superName;
+  /** Internal name of the super-class declared by this class; {@code null} for modules. */
+  @Nullable public final String superName;
 
   /** Internal names of the interfaces declared by this class. */
   public final String[] interfaces;
 
-  ClassHeader(int access, String className, String superName, String[] interfaces) {
+  ClassHeader(int access, String className, @Nullable String superName, String[] interfaces) {
     this.access = access;
     this.className = className;
     this.superName = superName;

class-match/src/main/java/datadog/instrument/classmatch/ClassOutline.java

@@ -6,6 +6,8 @@
 
 package datadog.instrument.classmatch;
 
+import javax.annotation.Nullable;
+
 /** Outlines a class; access modifiers, immediate class hierarchy, field, methods, annotations. */
 public final class ClassOutline extends ClassHeader {
 
@@ -21,7 +23,7 @@ public final class ClassOutline extends ClassHeader {
   ClassOutline(
       int access,
       String className,
-      String superName,
+      @Nullable String superName,
       String[] interfaces,
       FieldOutline[] fields,
       MethodOutline[] methods,

class-match/src/main/java/datadog/instrument/classmatch/package-info.java

@@ -0,0 +1,4 @@
+@ParametersAreNonnullByDefault
+package datadog.instrument.classmatch;
+
+import javax.annotation.ParametersAreNonnullByDefault;

field-inject/src/test/java/datadog/instrument/fieldinject/ObjectStoreIdsTest.java

@@ -1,9 +1,3 @@
-/*
- * Unless explicitly stated otherwise all files in this repository are licensed under the Apache-2.0 License.
- * This product includes software developed at Datadog (https://www.datadoghq.com/).
- * Copyright 2025-Present Datadog, Inc.
- */
-
 package datadog.instrument.fieldinject;
 
 import static datadog.instrument.fieldinject.ObjectStoreIds.objectStoreId;

field-inject/src/test/java/datadog/instrument/fieldinject/ObjectStoreTest.java

@@ -1,9 +1,3 @@
-/*
- * Unless explicitly stated otherwise all files in this repository are licensed under the Apache-2.0 License.
- * This product includes software developed at Datadog (https://www.datadoghq.com/).
- * Copyright 2025-Present Datadog, Inc.
- */
-
 package datadog.instrument.fieldinject;
 
 import static org.assertj.core.api.Assertions.assertThat;

utils/src/main/java/datadog/instrument/utils/ClassLoaderIndex.java

@@ -11,6 +11,8 @@
 import static datadog.instrument.utils.ClassLoaderKey.SYSTEM_CLASS_LOADER;
 import static datadog.instrument.utils.ClassLoaderKey.SYSTEM_CLASS_LOADER_KEY_ID;
 
+import javax.annotation.Nullable;
+
 /**
  * Semi-stable index of known {@link ClassLoader}s that guarantees a unique key-id for different
  * class-loaders. A class-loader may have more than one key-id over its life if it is temporarily
@@ -36,7 +38,7 @@ private ClassLoaderIndex() {}
    * @param cl the class-loader to index
    * @return key-id for the class-loader
    */
-  public static int getClassLoaderKeyId(ClassLoader cl) {
+  public static int getClassLoaderKeyId(@Nullable ClassLoader cl) {
     if (cl == BOOT_CLASS_LOADER) {
       return BOOT_CLASS_LOADER_KEY_ID;
     } else if (cl == SYSTEM_CLASS_LOADER) {

utils/src/main/java/datadog/instrument/utils/ClassLoaderValue.java

@@ -17,6 +17,7 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
 import java.util.function.BiConsumer;
+import javax.annotation.Nullable;
 
 /**
  * Lazily associate a computed value with (potentially) every {@link ClassLoader}. The computed
@@ -67,7 +68,7 @@ protected ClassLoaderValue() {
    * @see #get
    * @see #remove
    */
-  protected abstract V computeValue(ClassLoader cl);
+  protected abstract V computeValue(@Nullable ClassLoader cl);
 
   /**
    * Returns the value for the given class-loader. If no value has yet been computed, it is obtained
@@ -82,7 +83,7 @@ protected ClassLoaderValue() {
    * @see #remove
    * @see #computeValue
    */
-  public final V get(ClassLoader cl) {
+  public final V get(@Nullable ClassLoader cl) {
     if (cl == BOOT_CLASS_LOADER) {
       return getBootValue();
     } else if (cl == SYSTEM_CLASS_LOADER) {
@@ -101,7 +102,7 @@ public final V get(ClassLoader cl) {
    *
    * @param cl the class-loader whose value must be removed
    */
-  public final void remove(ClassLoader cl) {
+  public final void remove(@Nullable ClassLoader cl) {
     if (cl == BOOT_CLASS_LOADER) {
       bootValue = null;
     } else if (cl == SYSTEM_CLASS_LOADER) {

utils/src/main/java/datadog/instrument/utils/ClassNameTrie.java

@@ -19,6 +19,7 @@
 import java.util.List;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import javax.annotation.Nullable;
 
 /**
  * Immutable space-efficient trie that captures a mapping of package/class names to numbers.
@@ -120,8 +121,8 @@ public final class ClassNameTrie {
   /** The compressed trie. */
   private final char[] trieData;
 
-  /** Long jump offsets. */
-  private final int[] longJumps;
+  /** Long jump offsets; {@code null} if there are none. */
+  @Nullable private final int[] longJumps;
 
   /**
    * Returns the number in the trie the given class-name maps to.
@@ -153,7 +154,7 @@ public int apply(String key, int fromIndex) {
    * @param fromIndex the index in the class-name to start matching from
    * @return the number the class-name maps to; {@code -1} if not mapped
    */
-  public static int apply(char[] data, int[] longJumps, String key, int fromIndex) {
+  public static int apply(char[] data, @Nullable int[] longJumps, String key, int fromIndex) {
     int keyLength = key.length();
     int keyIndex = fromIndex;
     int dataIndex = 0;
@@ -272,7 +273,7 @@ public static ClassNameTrie readFrom(DataInput in) throws IOException {
     return new ClassNameTrie(trieData, longJumps);
   }
 
-  ClassNameTrie(char[] trieData, int[] longJumps) {
+  ClassNameTrie(char[] trieData, @Nullable int[] longJumps) {
     this.trieData = trieData;
     this.longJumps = longJumps;
   }

utils/src/main/java/datadog/instrument/utils/package-info.java

@@ -0,0 +1,4 @@
+@ParametersAreNonnullByDefault
+package datadog.instrument.utils;
+
+import javax.annotation.ParametersAreNonnullByDefault;