Minor changes

Author: S-Saranya1

codegen/src/main/java/software/amazon/awssdk/codegen/emitters/tasks/PackageInfoGeneratorTasks.java

@@ -91,14 +91,14 @@ private String generateCodeExamplesJavadoc(List<DocumentationUtils.ExampleData>
         }
 
         StringBuilder javadoc = new StringBuilder();
-        javadoc.append("<h3>Code Examples</h3>").append("\n");
+        javadoc.append("<h2>Code Examples</h2>").append("\n");
         javadoc.append("<p>The following code examples show how to use this service with the AWS SDK for Java v2:</p>")
                .append("\n");
 
         Map<String, String> categoryMapping = new java.util.LinkedHashMap<>();
         categoryMapping.put("Hello", "Getting Started");
-        categoryMapping.put("Api", "API Actions");
         categoryMapping.put("Basics", "Basics");
+        categoryMapping.put("Api", "API Actions");
         categoryMapping.put("Scenarios", "Scenarios");
         categoryMapping.put("Serverless examples", "Serverless Examples");
 
@@ -126,7 +126,7 @@ private String generateCodeExamplesJavadoc(List<DocumentationUtils.ExampleData>
 
     private void appendCategorySection(StringBuilder javadoc, String displayName,
                                        List<DocumentationUtils.ExampleData> categoryExamples) {
-        javadoc.append("<h4>").append(displayName).append("</h4>").append("\n");
+        javadoc.append("<h3>").append(displayName).append("</h3>").append("\n");
         javadoc.append("<ul>").append("\n");
 
         for (DocumentationUtils.ExampleData example : categoryExamples) {

codegen/src/main/java/software/amazon/awssdk/codegen/internal/DocumentationUtils.java

@@ -234,7 +234,7 @@ private static JsonNode getServiceNode(String serviceKey, String exampleMetaPath
         if (serviceNodeCache == null) {
             buildServiceCache(exampleMetaPath);
         }
-        return serviceNodeCache.get(serviceKey);
+        return serviceNodeCache != null ? serviceNodeCache.get(serviceKey) : null;
     }
 
     /**
@@ -244,7 +244,7 @@ private static Map<String, String> getNormalizedServiceKeyMap(String exampleMeta
         if (normalizedServiceKeyMap == null) {
             buildServiceCache(exampleMetaPath);
         }
-        return normalizedServiceKeyMap;
+        return normalizedServiceKeyMap != null ? normalizedServiceKeyMap : new HashMap<>();
     }
 
     /**