diff --git a/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache b/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache
index 1c52f7f245b2..eec283f3f0d3 100644
--- a/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache
@@ -173,13 +173,13 @@ export class {{classname}} {
      * @deprecated
      {{/isDeprecated}}
      */
-    public {{nickname}}({{^useSingleRequestParameter}}{{#allParams}}{{paramName}}{{^required}}?{{/required}}: {{{dataType}}}, {{/allParams}}{{/useSingleRequestParameter}}{{#useSingleRequestParameter}}{{#allParams.0}}requestParameters: {{#prefixParameterInterfaces}}{{classname}}{{/prefixParameterInterfaces}}{{operationIdCamelCase}}RequestParams, {{/allParams.0}}{{/useSingleRequestParameter}}observe?: 'body', reportProgress?: boolean, options?: {httpHeaderAccept?: {{#produces}}'{{{mediaType}}}'{{^-last}} | {{/-last}}{{/produces}}{{^produces}}undefined{{/produces}},{{#httpContextInOptions}} context?: HttpContext{{/httpContextInOptions}}{{#httpTransferCacheInOptions}}, transferCache?: boolean{{/httpTransferCacheInOptions}}}): Observable<{{#returnType}}{{{returnType}}}{{#isResponseTypeFile}}|undefined{{/isResponseTypeFile}}{{/returnType}}{{^returnType}}any{{/returnType}}>;
-    public {{nickname}}({{^useSingleRequestParameter}}{{#allParams}}{{paramName}}{{^required}}?{{/required}}: {{{dataType}}}, {{/allParams}}{{/useSingleRequestParameter}}{{#useSingleRequestParameter}}{{#allParams.0}}requestParameters: {{#prefixParameterInterfaces}}{{classname}}{{/prefixParameterInterfaces}}{{operationIdCamelCase}}RequestParams, {{/allParams.0}}{{/useSingleRequestParameter}}observe?: 'response', reportProgress?: boolean, options?: {httpHeaderAccept?: {{#produces}}'{{{mediaType}}}'{{^-last}} | {{/-last}}{{/produces}}{{^produces}}undefined{{/produces}},{{#httpContextInOptions}} context?: HttpContext{{/httpContextInOptions}}{{#httpTransferCacheInOptions}}, transferCache?: boolean{{/httpTransferCacheInOptions}}}): Observable<HttpResponse<{{#returnType}}{{{returnType}}}{{#isResponseTypeFile}}|undefined{{/isResponseTypeFile}}{{/returnType}}{{^returnType}}any{{/returnType}}>>;
-    public {{nickname}}({{^useSingleRequestParameter}}{{#allParams}}{{paramName}}{{^required}}?{{/required}}: {{{dataType}}}, {{/allParams}}{{/useSingleRequestParameter}}{{#useSingleRequestParameter}}{{#allParams.0}}requestParameters: {{#prefixParameterInterfaces}}{{classname}}{{/prefixParameterInterfaces}}{{operationIdCamelCase}}RequestParams, {{/allParams.0}}{{/useSingleRequestParameter}}observe?: 'events', reportProgress?: boolean, options?: {httpHeaderAccept?: {{#produces}}'{{{mediaType}}}'{{^-last}} | {{/-last}}{{/produces}}{{^produces}}undefined{{/produces}},{{#httpContextInOptions}} context?: HttpContext{{/httpContextInOptions}}{{#httpTransferCacheInOptions}}, transferCache?: boolean{{/httpTransferCacheInOptions}}}): Observable<HttpEvent<{{#returnType}}{{{returnType}}}{{#isResponseTypeFile}}|undefined{{/isResponseTypeFile}}{{/returnType}}{{^returnType}}any{{/returnType}}>>;
-    public {{nickname}}({{^useSingleRequestParameter}}{{#allParams}}{{paramName}}{{^required}}?{{/required}}: {{{dataType}}}, {{/allParams}}{{/useSingleRequestParameter}}{{#useSingleRequestParameter}}{{#allParams.0}}requestParameters: {{#prefixParameterInterfaces}}{{classname}}{{/prefixParameterInterfaces}}{{operationIdCamelCase}}RequestParams, {{/allParams.0}}{{/useSingleRequestParameter}}observe: any = 'body', reportProgress: boolean = false, options?: {httpHeaderAccept?: {{#produces}}'{{{mediaType}}}'{{^-last}} | {{/-last}}{{/produces}}{{^produces}}undefined{{/produces}},{{#httpContextInOptions}} context?: HttpContext{{/httpContextInOptions}}{{#httpTransferCacheInOptions}}, transferCache?: boolean{{/httpTransferCacheInOptions}}}): Observable<any> {
+    public {{nickname}}({{^useSingleRequestParameter}}{{#allParams}}{{paramName}}{{^required}}?{{/required}}: {{{dataType}}}, {{/allParams}}{{/useSingleRequestParameter}}{{#useSingleRequestParameter}}{{#allParams.0}}requestParameters{{^hasRequiredVars}}?{{/hasRequiredVars}}: {{#prefixParameterInterfaces}}{{classname}}{{/prefixParameterInterfaces}}{{operationIdCamelCase}}RequestParams, {{/allParams.0}}{{/useSingleRequestParameter}}observe?: 'body', reportProgress?: boolean, options?: {httpHeaderAccept?: {{#produces}}'{{{mediaType}}}'{{^-last}} | {{/-last}}{{/produces}}{{^produces}}undefined{{/produces}},{{#httpContextInOptions}} context?: HttpContext{{/httpContextInOptions}}{{#httpTransferCacheInOptions}}, transferCache?: boolean{{/httpTransferCacheInOptions}}}): Observable<{{#returnType}}{{{returnType}}}{{#isResponseTypeFile}}|undefined{{/isResponseTypeFile}}{{/returnType}}{{^returnType}}any{{/returnType}}>;
+    public {{nickname}}({{^useSingleRequestParameter}}{{#allParams}}{{paramName}}{{^required}}?{{/required}}: {{{dataType}}}, {{/allParams}}{{/useSingleRequestParameter}}{{#useSingleRequestParameter}}{{#allParams.0}}requestParameters{{^hasRequiredVars}}?{{/hasRequiredVars}}: {{#prefixParameterInterfaces}}{{classname}}{{/prefixParameterInterfaces}}{{operationIdCamelCase}}RequestParams, {{/allParams.0}}{{/useSingleRequestParameter}}observe?: 'response', reportProgress?: boolean, options?: {httpHeaderAccept?: {{#produces}}'{{{mediaType}}}'{{^-last}} | {{/-last}}{{/produces}}{{^produces}}undefined{{/produces}},{{#httpContextInOptions}} context?: HttpContext{{/httpContextInOptions}}{{#httpTransferCacheInOptions}}, transferCache?: boolean{{/httpTransferCacheInOptions}}}): Observable<HttpResponse<{{#returnType}}{{{returnType}}}{{#isResponseTypeFile}}|undefined{{/isResponseTypeFile}}{{/returnType}}{{^returnType}}any{{/returnType}}>>;
+    public {{nickname}}({{^useSingleRequestParameter}}{{#allParams}}{{paramName}}{{^required}}?{{/required}}: {{{dataType}}}, {{/allParams}}{{/useSingleRequestParameter}}{{#useSingleRequestParameter}}{{#allParams.0}}requestParameters{{^hasRequiredVars}}?{{/hasRequiredVars}}: {{#prefixParameterInterfaces}}{{classname}}{{/prefixParameterInterfaces}}{{operationIdCamelCase}}RequestParams, {{/allParams.0}}{{/useSingleRequestParameter}}observe?: 'events', reportProgress?: boolean, options?: {httpHeaderAccept?: {{#produces}}'{{{mediaType}}}'{{^-last}} | {{/-last}}{{/produces}}{{^produces}}undefined{{/produces}},{{#httpContextInOptions}} context?: HttpContext{{/httpContextInOptions}}{{#httpTransferCacheInOptions}}, transferCache?: boolean{{/httpTransferCacheInOptions}}}): Observable<HttpEvent<{{#returnType}}{{{returnType}}}{{#isResponseTypeFile}}|undefined{{/isResponseTypeFile}}{{/returnType}}{{^returnType}}any{{/returnType}}>>;
+    public {{nickname}}({{^useSingleRequestParameter}}{{#allParams}}{{paramName}}{{^required}}?{{/required}}: {{{dataType}}}, {{/allParams}}{{/useSingleRequestParameter}}{{#useSingleRequestParameter}}{{#allParams.0}}requestParameters{{^hasRequiredVars}}?{{/hasRequiredVars}}: {{#prefixParameterInterfaces}}{{classname}}{{/prefixParameterInterfaces}}{{operationIdCamelCase}}RequestParams, {{/allParams.0}}{{/useSingleRequestParameter}}observe: any = 'body', reportProgress: boolean = false, options?: {httpHeaderAccept?: {{#produces}}'{{{mediaType}}}'{{^-last}} | {{/-last}}{{/produces}}{{^produces}}undefined{{/produces}},{{#httpContextInOptions}} context?: HttpContext{{/httpContextInOptions}}{{#httpTransferCacheInOptions}}, transferCache?: boolean{{/httpTransferCacheInOptions}}}): Observable<any> {
 {{#allParams}}
 {{#useSingleRequestParameter}}
-        const {{paramName}} = requestParameters.{{paramName}};
+        const {{paramName}} = requestParameters{{^hasRequiredVars}}?{{/hasRequiredVars}}.{{paramName}};
 {{/useSingleRequestParameter}}
 {{#required}}
         if ({{paramName}} === null || {{paramName}} === undefined) {