added comments, fixed indentation

Author: inemtsev

modules/openapi-generator/src/main/resources/Java/libraries/native/api.mustache

@@ -56,7 +56,17 @@ import java.util.concurrent.CompletableFuture;
 {{>generatedAnnotation}}
 {{#operations}}
 public class {{classname}} {
+  /**
+   * Utility class for extending HttpRequest.Builder functionality.
+   */
   private static class HttpRequestBuilderExtensions {
+    /**
+     * Adds additional headers to the provided HttpRequest.Builder. Useful for adding method/endpoint specific headers.
+     *
+     * @param builder the HttpRequest.Builder to which headers will be added
+     * @param headers a map of header names and values to add; may be null
+     * @return the same HttpRequest.Builder instance with the additional headers set
+     */
     static HttpRequest.Builder withAdditionalHeaders(HttpRequest.Builder builder, Map<String, String> headers) {
         if (headers != null) {
             for (Map.Entry<String, String> entry : headers.entrySet()) {
@@ -282,7 +292,7 @@ public class {{classname}} {
   {{/isDeprecated}}
   public {{#returnType}}{{#asyncNative}}CompletableFuture<{{{returnType}}}>{{/asyncNative}}{{^asyncNative}}{{{returnType}}}{{/asyncNative}}{{/returnType}}{{^returnType}}{{#asyncNative}}CompletableFuture<Void>{{/asyncNative}}{{^asyncNative}}void{{/asyncNative}}{{/returnType}} {{operationId}}({{#allParams}}{{>nullable_var_annotations}} {{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#hasParams}}, {{/hasParams}}Map<String, String> headers) throws ApiException {
     {{^asyncNative}}
-          {{#returnType}}ApiResponse<{{{.}}}> localVarResponse = {{/returnType}}{{operationId}}WithHttpInfo({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#hasParams}}, {{/hasParams}}headers);
+    {{#returnType}}ApiResponse<{{{.}}}> localVarResponse = {{/returnType}}{{operationId}}WithHttpInfo({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#hasParams}}, {{/hasParams}}headers);
     {{#returnType}}
     return localVarResponse.getData();
     {{/returnType}}