IWF-518: Bypass constructor when using newRpcStub (#293)

Author: lwolczynski

build.gradle

@@ -60,6 +60,7 @@ dependencies {
     implementation 'io.swagger:swagger-core:1.6.6'
     implementation "org.openapitools:jackson-databind-nullable:0.2.1"
     implementation "net.bytebuddy:byte-buddy:1.14.4"
+    implementation "org.objenesis:objenesis:3.4"
 
     // jaskson
     implementation "com.fasterxml.jackson.datatype:jackson-datatype-jsr310"

src/main/java/io/iworkflow/core/Client.java

@@ -20,6 +20,8 @@
 import net.bytebuddy.ByteBuddy;
 import net.bytebuddy.implementation.MethodDelegation;
 import net.bytebuddy.matcher.ElementMatchers;
+import org.objenesis.Objenesis;
+import org.objenesis.ObjenesisStd;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
@@ -802,21 +804,8 @@ public <T> T newRpcStub(Class<T> workflowClassForRpc, String workflowId, String
                 .load(getClass().getClassLoader())
                 .getLoaded();
 
-        T result;
-        try {
-            if(dynamicType.getConstructors().length ==0){
-                throw new WorkflowDefinitionException("workflow must define at least a constructor");
-            }
-            final Constructor<?> constructor = dynamicType.getConstructors()[0];
-            final int parameterCount = constructor.getParameterCount();
-            final Object[] params = new Object[parameterCount];
-
-            result = (T) constructor.newInstance(params);
-        } catch (InvocationTargetException | InstantiationException | IllegalAccessException e) {
-            throw new IllegalStateException(e);
-        }
-
-        return result;
+        Objenesis objenesis = new ObjenesisStd();
+        return (T) objenesis.newInstance(dynamicType);
     }
 
     /**