Fix javadoc error

Created by: jmini

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\. If contributing template-only or documentation-only changes which will change sample output, be sure to build the project first.
• Filed the PR against the correct branch: master, 4.1.x, 5.0.x. Default: master.
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Description of the PR

This small PR fixes a javadoc bloc to fix following warning:

Javadoc: Missing tag for declared exception: Exception

modules/openapi-generator/src/test/java/org/openapitools/codegen/asciidoc/AsciidocSampleGeneratorTest.java

@@ -16,7 +16,10 @@ import org.testng.annotations.Test;
 
 public class AsciidocSampleGeneratorTest {
 
-    /** ensure api-docs.json includes sample and spec files into markup. */
+    /** 
+     * ensure api-docs.json includes sample and spec files into markup.
+     * @throws Exception generic exception
+     */
     @Test
     public void testSampleAsciidocMarkupGenerationFromJsonWithSpecsAndSamples() throws Exception {