Adding some implementation comments
MODIFY
dd-java-agent/instrumentation/jax-rs-annotations-2/filter-jersey/src/main/java/datadog/trace/instrumentation/jaxrs2/JerseyRequestContextInstrumentation.java
dd-java-agent/instrumentation/jax-rs-annotations-2/filter-jersey/src/main/java/datadog/trace/instrumentation/jaxrs2/JerseyRequestContextInstrumentation.java
@@ -9,7 +9,15 @@ import javax.ws.rs.container.ResourceInfo;
import javax.ws.rs.core.UriInfo;
import net.bytebuddy.asm.Advice;
-/** Jersey specific filter instrumentation. */
+/**
+ * Jersey specific context instrumentation.
+ *
+ * <p>JAX-RS does not define a way to get the matched resource method from the <code>
+ * ContainerRequestContext</code>
+ *
+ * <p>In the Jersey implementation, <code>UriInfo</code> implements <code>ResourceInfo</code>. The
+ * matched resource method can be retrieved from that object
+ */
@AutoService(Instrumenter.class)
public class JerseyRequestContextInstrumentation extends AbstractRequestContextInstrumentation {
public static class ContainerRequestContextAdvice {

MODIFY
dd-java-agent/instrumentation/jax-rs-annotations-2/filter-resteasy-3.0/src/main/java/datadog/trace/instrumentation/jaxrs2/Resteasy30RequestContextInstrumentation.java
dd-java-agent/instrumentation/jax-rs-annotations-2/filter-resteasy-3.0/src/main/java/datadog/trace/instrumentation/jaxrs2/Resteasy30RequestContextInstrumentation.java
@@ -9,6 +9,16 @@ import net.bytebuddy.asm.Advice;
import org.jboss.resteasy.core.ResourceMethodInvoker;
import org.jboss.resteasy.core.interception.PostMatchContainerRequestContext;
+/**
+ * RESTEasy specific context instrumentation.
+ *
+ * <p>JAX-RS does not define a way to get the matched resource method from the <code>
+ * ContainerRequestContext</code>
+ *
+ * <p>In the RESTEasy implementation, <code>ContainerRequestContext</code> is implemented by <code>
+ * PostMatchContainerRequestContext</code>. This class provides a way to get the matched resource
+ * method through <code>getResourceMethod()</code>.
+ */
@AutoService(Instrumenter.class)
public class Resteasy30RequestContextInstrumentation extends AbstractRequestContextInstrumentation {
public static class ContainerRequestContextAdvice {

MODIFY
dd-java-agent/instrumentation/jax-rs-annotations-2/filter-resteasy-3.1/src/main/java/datadog/trace/instrumentation/jaxrs2/Resteasy31RequestContextInstrumentation.java
dd-java-agent/instrumentation/jax-rs-annotations-2/filter-resteasy-3.1/src/main/java/datadog/trace/instrumentation/jaxrs2/Resteasy31RequestContextInstrumentation.java
@@ -9,6 +9,16 @@ import net.bytebuddy.asm.Advice;
import org.jboss.resteasy.core.ResourceMethodInvoker;
import org.jboss.resteasy.core.interception.jaxrs.PostMatchContainerRequestContext;
+/**
+ * RESTEasy specific context instrumentation.
+ *
+ * <p>JAX-RS does not define a way to get the matched resource method from the <code>
+ * ContainerRequestContext</code>
+ *
+ * <p>In the RESTEasy implementation, <code>ContainerRequestContext</code> is implemented by <code>
+ * PostMatchContainerRequestContext</code>. This class provides a way to get the matched resource
+ * method through <code>getResourceMethod()</code>.
+ */
@AutoService(Instrumenter.class)
public class Resteasy31RequestContextInstrumentation extends AbstractRequestContextInstrumentation {
public static class ContainerRequestContextAdvice {

MODIFY
dd-java-agent/instrumentation/jax-rs-annotations-2/src/main/java/datadog/trace/instrumentation/jaxrs2/ContainerRequestFilterInstrumentation.java
dd-java-agent/instrumentation/jax-rs-annotations-2/src/main/java/datadog/trace/instrumentation/jaxrs2/ContainerRequestFilterInstrumentation.java
@@ -19,7 +19,10 @@ import net.bytebuddy.description.method.MethodDescription;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.matcher.ElementMatcher;
-/** This adds the filter class name to the request properties */
+/**
+ * This adds the filter class name to the request properties. The class name is used by <code>
+ * DefaultRequestContextInstrumentation</code>
+ */
@AutoService(Instrumenter.class)
public class ContainerRequestFilterInstrumentation extends Instrumenter.Default {

MODIFY
dd-java-agent/instrumentation/jax-rs-annotations-2/src/main/java/datadog/trace/instrumentation/jaxrs2/DefaultRequestContextInstrumentation.java
dd-java-agent/instrumentation/jax-rs-annotations-2/src/main/java/datadog/trace/instrumentation/jaxrs2/DefaultRequestContextInstrumentation.java
@@ -14,8 +14,13 @@ import javax.ws.rs.container.ContainerRequestContext;
import net.bytebuddy.asm.Advice;
/**
- * Create a generic jax-rs.request.abort span based on the class name of the filter Implementation
- * specifc instrumentations can override tag values
+ * Default context instrumentation.
+ *
+ * <p>JAX-RS does not define a way to get the matched resource method from the <code>
+ * ContainerRequestContext</code>
+ *
+ * <p>This default instrumentation uses the class name of the filter to create the span. More
+ * specific instrumentations may override this value.
*/
@AutoService(Instrumenter.class)
public class DefaultRequestContextInstrumentation extends AbstractRequestContextInstrumentation {

Adding some implementation comments