Mark Maven plugin as threadSafe

Author: vojtechhabarta

typescript-generator-maven-plugin/src/main/java/cz/habarta/typescript/generator/maven/GenerateMojo.java

@@ -14,7 +14,7 @@
  * Generates TypeScript declaration file from specified java classes.
  * For more information see README and Wiki on GitHub.
  */
-@Mojo(name = "generate", defaultPhase = LifecyclePhase.PROCESS_CLASSES, requiresDependencyResolution = ResolutionScope.COMPILE)
+@Mojo(name = "generate", defaultPhase = LifecyclePhase.PROCESS_CLASSES, requiresDependencyResolution = ResolutionScope.COMPILE, threadSafe = true)
 public class GenerateMojo extends AbstractMojo {
 
     /**