If one wants to generate the code from an openapi file, OpenApi Generator Plugin for Maven is quite handy.
I am using the OpenAPI Generator Plugin for Maven to generate server code for a demo Spring Boot application created with Spring Initializr. When the interfaceOnly flag is set to false, the generator creates a SpringDocConfiguration class that includes a bean for io.swagger.v3.oas.models.OpenAPI, which the Swagger UI uses. However, it also generates an org.openapitools.OpenApiGeneratorApplication class with a @SpringBootApplication annotation. This class conflicts with my DemoApplication.java, which has its own @SpringBootApplication annotation.
when I try to build the project, I encounter the following error due to multiple main classes:
[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:3.2.5:repackage (repackage) on project demo: Execution repackage of goal org.springframework.boot:spring-boot-maven-plugin:3.2.5:repackage failed: Unable to find a single main class from the following candidates [org.openapitools.OpenApiGeneratorApplication, com.example.demo.DemoApplication] -> [Help 1]
How can I ignore the OpenApiGeneratorApplication.java file during generation? I would like to check out the java class annotated with @SpringBootApplication to have better control.
My pom.xml is configured as follows:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>3.2.5</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>demo</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>22</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springdoc</groupId>
<artifactId>springdoc-openapi-starter-webmvc-ui</artifactId>
<version>2.5.0</version>
</dependency>
<dependency>
<groupId>jakarta.validation</groupId>
<artifactId>jakarta.validation-api</artifactId>
</dependency>
<dependency>
<groupId>io.swagger.core.v3</groupId>
<artifactId>swagger-annotations</artifactId>
<version>2.2.21</version>
</dependency>
<dependency>
<groupId>io.swagger.core.v3</groupId>
<artifactId>swagger-models</artifactId>
<version>2.2.21</version>
</dependency>
<dependency>
<groupId>org.openapitools</groupId>
<artifactId>jackson-databind-nullable</artifactId>
<version>0.2.0</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.openapitools</groupId>
<artifactId>openapi-generator-maven-plugin</artifactId>
<version>7.5.0</version>
<executions>
<execution>
<goals>
<goal>generate</goal>
</goals>
<configuration>
<configHelp>false</configHelp>
<inputSpec>
${project.basedir}/src/main/resources/petstore.yaml
</inputSpec>
<openapiGeneratorIgnoreList>OpenApiGeneratorApplication.java</openapiGeneratorIgnoreList>
<generatorName>spring</generatorName>
<apiPackage>com.example.demo.api</apiPackage>
<modelPackage>com.example.demo.api.model</modelPackage>
<configOptions>
<useSpringBoot3>true</useSpringBoot3>
<delegatePattern>false</delegatePattern>
<interfaceOnly>false</interfaceOnly>
</configOptions>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
I tried to use the openapi-generator-ignore file but together with the property openapiGeneratorIgnoreList, but it still generates the class.
For easy testing I will temporarily leave this project to checkout: [git@github.com:legolaz8451/openapi-generator-spring-demo.git](git@github.com:legolaz8451/openapi-generator-spring-demo.git)
To avoid the generation of the @SpringBootApplication class from Spring, one has to add the class to the openapiGeneratorIgnoreList inside the configuration element like this:
<openapiGeneratorIgnoreList>
src/main/java/org/openapitools/OpenApiGeneratorApplication.java
</openapiGeneratorIgnoreList>