[BUG][Maven] Maven plugin ignores generateApis

Note: This bug is encountered when using the Maven plugin, but it may be that it's a bug in the generator itself; I'm not sure whether the plugin is invoking it correctly.

Description

The Maven plugin version 4.2.1 ignores the documented generateApis and generateModels configuration parameters.

I am trying to separate the data types and the generated REST client into Maven modules, using these parameters to generate the code in the appropriate place. However, the Maven plugin appears not to inspect them at all.

This is not related to any specific spec file but is a matter of the generator invocation itself.

openapi-generator version

org.openapitools:openapi-generator-maven-plugin:4.2.1:generate

Steps to reproduce

I used the following POM plugin declaration:

<plugin>
    <groupId>org.openapitools</groupId>
    <artifactId>openapi-generator-maven-plugin</artifactId>
    <version>4.2.1</version>
    <executions>
        <execution>
            <goals>
                <goal>generate</goal>
            </goals>
            <configuration>
                <inputSpec>${project.basedir}/src/main/openapi/equipment.yaml</inputSpec>
                <generatorName>java</generatorName>
                <modelPackage>com.foo.equipment.api.openapi</modelPackage>
                <generateApis>false</generateApis>
                <apiPackage>foo</apiPackage>
                <configOptions>
                    <library>resttemplate</library>
                    <java8>true</java8>
                    <dateLibrary>java8</dateLibrary>
                </configOptions>
            </configuration>
        </execution>
    </executions>
</plugin>

When running using mvn -X, the mojo configuration model reflects the documented parameters:

<configuration>
  <!-- snip -->
  <configOptions>
    <library>resttemplate</library>
    <java8>true</java8>
    <dateLibrary>java8</dateLibrary>
  </configOptions>
  <!-- snip -->
  <generateApiDocumentation>${openapi.generator.maven.plugin.generateApiDocumentation}</generateApiDocumentation>
  <generateApiTests>${openapi.generator.maven.plugin.generateApiTests}</generateApiTests>
  <generateApis>false</generateApis>
  <generateModelDocumentation>${openapi.generator.maven.plugin.generateModelDocumentation}</generateModelDocumentation>
  <generateModelTests>${openapi.generator.maven.plugin.generateModelTests}</generateModelTests>
  <generateModels>${openapi.generator.maven.plugin.generateModels}</generateModels>
  <generateSupportingFiles>${openapi.generator.maven.plugin.generateSupportingFiles}</generateSupportingFiles>
  <generatorName>java</generatorName>
  <!-- snip -->
</configuration>

The configurator applies the generateApis setting:

[DEBUG] Configuring mojo 'org.openapitools:openapi-generator-maven-plugin:4.2.1:generate' with basic configurator -->
[DEBUG]   (f) addCompileSourceRoot = true
[DEBUG]   (f) additionalProperties = []
[DEBUG]   (f) configOptions = {dateLibrary=java8, java8=true, library=resttemplate}
[DEBUG]   (f) engine = mustache
[DEBUG]   (f) generateApis = false
[DEBUG]   (f) generatorName = java
[DEBUG]   (f) importMappings = []
[DEBUG]   (f) inputSpec = <redacted>
[DEBUG]   (f) instantiationTypes = []
[DEBUG]   (f) languageSpecificPrimitives = []
[DEBUG]   (f) modelPackage = com.foo.equipment.api.openapi
[DEBUG]   (f) output = <redacted>
[DEBUG]   (f) project = <redacted>
[DEBUG]   (f) reservedWordsMappings = []
[DEBUG]   (f) serverVariableOverrides = []
[DEBUG]   (f) skip = false
[DEBUG]   (f) skipIfSpecIsUnchanged = false
[DEBUG]   (f) typeMappings = []
[DEBUG]   (f) verbose = false
[DEBUG] -- end configuration --

Nevertheless, the generator generates a REST client (using an incorrectly "derived" package name):

[INFO] OpenAPI Generator: java (client)
[INFO] Generator 'java' is considered stable.
[INFO] Environment variable JAVA_POST_PROCESS_FILE not defined so the Java code may not be properly formatted. To define it, try 'export JAVA_POST_PROCESS_FILE="/usr/local/bin/clang-format -i"' (Linux/Mac)
[INFO] NOTE: To enable file post-processing, 'enablePostProcessFile' must be set to `true` (--enable-post-process-file for CLI).
[INFO] Invoker Package Name, originally not set, is now derived from model package name: com.foo.equipment.api

and the build fails because of missing dependencies.

The inverse does not seem to be true; i.e., the generateModels=false setting is respected.

Suggest a fix

It would be useful for the Maven plugin to log the exact config it is passing to DefaultGenerator at DEBUG; even using mvn -X does not provide output useful to debugging this problem.

Start by reproducing the Maven plugin configuration with generateApis=false and generateModels=false, then trace how the plugin invokes DefaultGenerator. Compare the handling of both settings and inspect the generated output and DEBUG logging. Done means generateApis=false prevents REST client generation and the configuration passed to DefaultGenerator is diagnosable.