diff --git a/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/Instrumenter.java b/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/Instrumenter.java
index f532086ae4..1ec4562b57 100644
--- a/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/Instrumenter.java
+++ b/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/Instrumenter.java
@@ -217,11 +217,13 @@ public interface Instrumenter {
     public abstract Map<? extends ElementMatcher<? super MethodDescription>, String> transformers();
 
     /**
-     * A map of {class-name -> context-class-name}. Keys (and their subclasses) will be associated
-     * with a context of the value.
+     * Context stores to define for this instrumentation.
+     *
+     * <p>A map of {class-name -> context-class-name}. Keys (and their subclasses) will be
+     * associated with a context of the value.
      */
     public Map<String, String> contextStore() {
-      return Collections.EMPTY_MAP;
+      return Collections.emptyMap();
     }
 
     protected boolean defaultEnabled() {
diff --git a/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/bytebuddy/matcher/SafeExtendsClassMatcher.java b/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/bytebuddy/matcher/SafeExtendsClassMatcher.java
index 9438be49e8..ddce190fd6 100644
--- a/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/bytebuddy/matcher/SafeExtendsClassMatcher.java
+++ b/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/bytebuddy/matcher/SafeExtendsClassMatcher.java
@@ -28,4 +28,9 @@ class SafeExtendsClassMatcher<T extends TypeDescription>
     }
     return false;
   }
+
+  @Override
+  public String toString() {
+    return "safeExtendsClass(" + matcher + ")";
+  }
 }
diff --git a/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/context/FieldBackedProvider.java b/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/context/FieldBackedProvider.java
index 522e8e6cf9..e8ab3ab7ec 100644
--- a/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/context/FieldBackedProvider.java
+++ b/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/context/FieldBackedProvider.java
@@ -127,8 +127,8 @@ public class FieldBackedProvider implements InstrumentationContextProvider {
   @Override
   public AgentBuilder.Identified.Extendable instrumentationTransformer(
       AgentBuilder.Identified.Extendable builder) {
-    if (instrumenter.contextStore().size() > 0) {
-      /**
+    if (!instrumenter.contextStore().isEmpty()) {
+      /*
        * Install transformer that rewrites accesses to context store with specialized bytecode that
        * invokes appropriate storage implementation.
        */
@@ -304,14 +304,14 @@ public class FieldBackedProvider implements InstrumentationContextProvider {
 
   private AgentBuilder.Identified.Extendable injectHelpersIntoBootstrapClassloader(
       AgentBuilder.Identified.Extendable builder) {
-    /**
+    /*
      * We inject into bootstrap classloader because field accessor interfaces are needed by context
      * store implementations. Unfortunately this forces us to remove stored type checking because
      * actual classes may not be available at this point.
      */
     builder = builder.transform(fieldAccessorInterfacesInjector);
 
-    /**
+    /*
      * We inject context store implementation into bootstrap classloader because same implementation
      * may be used by different instrumentations and it has to use same static map in case of
      * fallback to map-backed storage.
@@ -348,7 +348,7 @@ public class FieldBackedProvider implements InstrumentationContextProvider {
 
     if (fieldInjectionEnabled) {
       for (final Map.Entry<String, String> entry : instrumenter.contextStore().entrySet()) {
-        /**
+        /*
          * For each context store defined in a current instrumentation we create an agent builder
          * that injects necessary fields.
          */
@@ -363,7 +363,7 @@ public class FieldBackedProvider implements InstrumentationContextProvider {
                 .and(not(isAnnotatedWith(named("javax.decorator.Decorator"))))
                 .transform(AgentBuilder.Transformer.NoOp.INSTANCE);
 
-        /**
+        /*
          * We inject helpers here as well as when instrumentation is applied to ensure that helpers
          * are present even if instrumented classes are not loaded, but classes with state fields
          * added are loaded (e.g. sun.net.www.protocol.https.HttpsURLConnectionImpl).
@@ -388,7 +388,7 @@ public class FieldBackedProvider implements InstrumentationContextProvider {
           final JavaModule module,
           final Class<?> classBeingRedefined,
           final ProtectionDomain protectionDomain) {
-        /**
+        /*
          * The idea here is that we can add fields if class is just being loaded
          * (classBeingRedefined == null) and we have to add same fields again if class we added
          * fields before is being transformed again. Note: here we assume that Class#getInterfaces()