fix vertxFuture setting (#21176)

Author: martin-mfg

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java

@@ -137,6 +137,7 @@ public class JavaClientCodegen extends AbstractJavaCodegen
     @Setter protected String gradleProperties;
     @Setter protected String errorObjectType;
     @Getter @Setter protected boolean failOnUnknownProperties = false;
+    @Setter protected boolean supportVertxFuture = false;
     protected String authFolder;
     /**
      * Serialization library.
@@ -244,7 +245,7 @@ public JavaClientCodegen() {
         cliOptions.add(CliOption.newBoolean(SUPPORT_URL_QUERY, "Generate toUrlQueryString in POJO (default to true). Available on `native`, `apache-httpclient` libraries."));
         cliOptions.add(CliOption.newBoolean(USE_ENUM_CASE_INSENSITIVE, "Use `equalsIgnoreCase` when String for enum comparison", useEnumCaseInsensitive));
         cliOptions.add(CliOption.newBoolean(FAIL_ON_UNKNOWN_PROPERTIES, "Fail Jackson de-serialization on unknown properties", this.failOnUnknownProperties));
-        cliOptions.add(CliOption.newBoolean(SUPPORT_VERTX_FUTURE, "Also generate api methods that return a vertx Future instead of taking a callback. Only `vertx` supports this option. Requires vertx 4 or greater."));
+        cliOptions.add(CliOption.newBoolean(SUPPORT_VERTX_FUTURE, "Also generate api methods that return a vertx Future instead of taking a callback. Only `vertx` supports this option. Requires vertx 4 or greater.", this.supportVertxFuture));
 
         supportedLibraries.put(JERSEY2, "HTTP client: Jersey client 2.25.1. JSON processing: Jackson 2.17.1");
         supportedLibraries.put(JERSEY3, "HTTP client: Jersey client 3.1.1. JSON processing: Jackson 2.17.1");
@@ -421,6 +422,7 @@ public void processOpts() {
         convertPropertyToStringAndWriteBack(ERROR_OBJECT_TYPE, this::setErrorObjectType);
         convertPropertyToBooleanAndWriteBack(WEBCLIENT_BLOCKING_OPERATIONS, op -> webclientBlockingOperations = op);
         convertPropertyToBooleanAndWriteBack(FAIL_ON_UNKNOWN_PROPERTIES, this::setFailOnUnknownProperties);
+        convertPropertyToBooleanAndWriteBack(SUPPORT_VERTX_FUTURE, this::setSupportVertxFuture);
 
         // add URL query deepObject support to native, apache-httpclient by default
         if (!additionalProperties.containsKey(SUPPORT_URL_QUERY)) {