Mark interfaces in trace/data immutable (#2729)

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/data/EventData.java

@@ -7,7 +7,10 @@ package io.opentelemetry.sdk.trace.data;
 
 import io.opentelemetry.api.common.Attributes;
 import io.opentelemetry.sdk.trace.SpanLimits;
+import javax.annotation.concurrent.Immutable;
 
+/** Data representation of a event. */
+@Immutable
 public interface EventData {
 
   /**

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/data/ImmutableEventData.java

@@ -10,8 +10,8 @@ import io.opentelemetry.api.common.Attributes;
 import javax.annotation.concurrent.Immutable;
 
 /** An immutable implementation of the {@link EventData}. */
-@Immutable
 @AutoValue
+@Immutable
 abstract class ImmutableEventData implements EventData {
 
   /**

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/data/ImmutableLinkData.java

@@ -11,8 +11,8 @@ import io.opentelemetry.api.trace.SpanContext;
 import javax.annotation.concurrent.Immutable;
 
 /** An immutable implementation of {@link LinkData}. */
-@Immutable
 @AutoValue
+@Immutable
 abstract class ImmutableLinkData implements LinkData {
   private static final Attributes DEFAULT_ATTRIBUTE_COLLECTION = Attributes.empty();
   private static final int DEFAULT_ATTRIBUTE_COUNT = 0;

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/data/LinkData.java

@@ -8,13 +8,15 @@ package io.opentelemetry.sdk.trace.data;
 import io.opentelemetry.api.common.Attributes;
 import io.opentelemetry.api.trace.SpanContext;
 import io.opentelemetry.sdk.trace.SpanLimits;
+import javax.annotation.concurrent.Immutable;
 
 /**
- * Data representation of a Link.
+ * Data representation of a link.
  *
  * <p>Used (for example) in batching operations, where a single batch handler processes multiple
  * requests from different traces. Link can be also used to reference spans from the same trace.
  */
+@Immutable
 public interface LinkData {
 
   /**

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/data/StatusData.java

@@ -8,11 +8,13 @@ package io.opentelemetry.sdk.trace.data;
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.StatusCode;
 import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
 
 /**
  * Defines the status of a {@link Span} by providing a standard {@link StatusCode} in conjunction
  * with an optional descriptive message.
  */
+@Immutable
 public interface StatusData {
 
   /**