swagger-codegen-maven plugin 3.1.7 -SpringMvcApiReader parseMethod Nullpointer

[ERROR] Failed to execute goal com.github.kongchen:swagger-maven-plugin:3.1.7:generate (default) on project disp-web: null: MojoExecutionException: NullPointerException -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal com.github.kongchen:swagger-maven-plugin:3.1.7:generate (default) on project disp-web: null
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:212)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:863)
	at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
	at org.apache.maven.cli.MavenCli.main(MavenCli.java:199)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
	at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
	at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
Caused by: org.apache.maven.plugin.MojoExecutionException
	at com.github.kongchen.swagger.docgen.mavenplugin.ApiDocumentMojo.execute(ApiDocumentMojo.java:133)
	at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:207)
	... 20 more
Caused by: java.lang.NullPointerException
	at com.github.kongchen.swagger.docgen.reader.SpringMvcApiReader.parseMethod(SpringMvcApiReader.java:324)
	at com.github.kongchen.swagger.docgen.reader.SpringMvcApiReader.read(SpringMvcApiReader.java:131)
	at com.github.kongchen.swagger.docgen.reader.SpringMvcApiReader.read(SpringMvcApiReader.java:74)
	at com.github.kongchen.swagger.docgen.AbstractDocumentSource.loadDocuments(AbstractDocumentSource.java:104)
	at com.github.kongchen.swagger.docgen.mavenplugin.ApiDocumentMojo.execute(ApiDocumentMojo.java:96)
	... 22 more

This happens when I add a @Pathvariable in my method. My method signature is as following:

@ApiOperation(value = "findAllTemplateThirdParty", notes = "Find all TemplateThirdParty Resources", response = TemplateThirdPartyResponse.class, tags = { "Template Resource" })
@ApiResponses(value = { 
	@ApiResponse(code = 200, message = "OK", response = TemplateThirdPartyResponse.class),
	@ApiResponse(code = 400, message = "BAD REQUEST", response = ApiResponseMessage.class),
	@ApiResponse(code = 401, message = "UNAUTHORIZED", response = Void.class),
	@ApiResponse(code = 404, message = "NOT FOUND", response = Void.class) })
@RequestMapping(value = "/admin/templates/{templateId}/thirdParties", 
	produces = { "application/json", "application/hal+json", "text/uri-list", "application/x-spring-data-compact+json" },
	consumes = { "application/json" }, method = RequestMethod.GET)
ResponseEntity<PagedResources<TemplateThirdPartyResponse>> findAllTemplateThirdPartyUsingGET(
	@ApiParam(value = "templateId", required = true) @PathVariable Integer templateId,
	@QuerydslPredicate(root = entities.TemplateThirdParty.class) Predicate predicate,
	@PageableDefault(sort = { "id" }) Pageable pageable,
	@RequestParam MultiValueMap<String, String> parameters);

Without the @Pathvariable, the swagger-codegen runs fine but not acceptable for me.
Please could you investigate the underlying issue?

Start at SpringMvcApiReader.parseMethod around line 324 and follow its callers in SpringMvcApiReader.read and AbstractDocumentSource.loadDocuments. Reproduce the Maven generation failure with the shown @PathVariable method signature, then identify the null value and verify generation succeeds while preserving the path variable in the generated API documentation.