Merge pull request #1100 from swagger-api/codegen-issue-9509

avoid double pattern property assignment in order to fix issue

Author: HugoMario

src/main/java/io/swagger/codegen/v3/generators/util/OpenAPIUtil.java

@@ -22,7 +22,9 @@ public static void addPropertiesFromRef(OpenAPI openAPI, Schema refSchema, Codeg
         if (schema == null) {
             return;
         }
-        codegenProperty.pattern = schema.getPattern();
+        if (StringUtils.isBlank(codegenProperty.pattern)) {
+            codegenProperty.pattern = schema.getPattern();
+        }
         codegenProperty.minLength = schema.getMinLength();
         codegenProperty.maxLength = schema.getMaxLength();
         if (codegenProperty.pattern != null || codegenProperty.minLength != null || codegenProperty.maxLength != null) {