Apply review comments

Author: lukasz-antoniak

core/src/main/java/com/datastax/oss/driver/api/core/loadbalancing/LoadBalancingPolicy.java

@@ -24,6 +24,7 @@
 import com.datastax.oss.driver.api.core.tracker.RequestTracker;
 import edu.umd.cs.findbugs.annotations.NonNull;
 import edu.umd.cs.findbugs.annotations.Nullable;
+import java.util.Collections;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Queue;
@@ -78,8 +79,8 @@ default Optional<RequestTracker> getRequestTracker() {
 
   /** Returns map containing details that impact C* node connectivity. */
   @NonNull
-  default Optional<Map<String, ?>> getStartupConfiguration() {
-    return Optional.empty();
+  default Map<String, ?> getStartupConfiguration() {
+    return Collections.emptyMap();
   }
 
   /**

core/src/main/java/com/datastax/oss/driver/internal/core/context/StartupOptionsBuilder.java

@@ -159,10 +159,10 @@ private Optional<String> driverBaggage() {
     ImmutableMap.Builder<String, Object> builder = new ImmutableMap.Builder<>();
     for (Map.Entry<String, LoadBalancingPolicy> entry :
         context.getLoadBalancingPolicies().entrySet()) {
-      entry
-          .getValue()
-          .getStartupConfiguration()
-          .ifPresent(baggage -> builder.put(entry.getKey(), baggage));
+      Map<String, ?> config = entry.getValue().getStartupConfiguration();
+      if (!config.isEmpty()) {
+        builder.put(entry.getKey(), config);
+      }
     }
     try {
       return Optional.of(mapper.writeValueAsString(builder.build()));

core/src/main/java/com/datastax/oss/driver/internal/core/loadbalancing/BasicLoadBalancingPolicy.java

@@ -162,7 +162,7 @@ public String getLocalDatacenter() {
 
   @NonNull
   @Override
-  public Optional<Map<String, ?>> getStartupConfiguration() {
+  public Map<String, ?> getStartupConfiguration() {
     ImmutableMap.Builder<String, Object> builder = new ImmutableMap.Builder<>();
     if (localDc != null) {
       builder.put("localDc", localDc);
@@ -185,8 +185,7 @@ public String getLocalDatacenter() {
     if (maxNodesPerRemoteDc > 0) {
       builder.put("maxNodesPerRemoteDc", maxNodesPerRemoteDc);
     }
-    return Optional.of(
-        ImmutableMap.of(BasicLoadBalancingPolicy.class.getSimpleName(), builder.build()));
+    return ImmutableMap.of(BasicLoadBalancingPolicy.class.getSimpleName(), builder.build());
   }
 
   /** @return The nodes currently considered as live. */

core/src/main/java/com/datastax/oss/driver/internal/core/loadbalancing/DefaultLoadBalancingPolicy.java

@@ -39,7 +39,6 @@
 import edu.umd.cs.findbugs.annotations.NonNull;
 import edu.umd.cs.findbugs.annotations.Nullable;
 import java.util.BitSet;
-import java.util.Collections;
 import java.util.Map;
 import java.util.Optional;
 import java.util.OptionalLong;
@@ -355,11 +354,10 @@ private boolean hasSufficientResponses(long now) {
 
   @NonNull
   @Override
-  public Optional<Map<String, ?>> getStartupConfiguration() {
-    Map<String, ?> parent = super.getStartupConfiguration().orElse(Collections.emptyMap());
-    return Optional.of(
-        ImmutableMap.of(
-            DefaultLoadBalancingPolicy.class.getSimpleName(),
-            parent.get(BasicLoadBalancingPolicy.class.getSimpleName())));
+  public Map<String, ?> getStartupConfiguration() {
+    Map<String, ?> parent = super.getStartupConfiguration();
+    return ImmutableMap.of(
+        DefaultLoadBalancingPolicy.class.getSimpleName(),
+        parent.get(BasicLoadBalancingPolicy.class.getSimpleName()));
   }
 }