[Fix #1553] Initialize call field in generated Callxxx classes (#1555)

When using DSL, the call field is not set unless the DSL method
implementation invokes either setCall or withCall, which current
implementation is not actually doing, leading to the reported issue.

Rather than changing a lot of fluent dsl classes both in sdk and
experimental (recently moved to QFlow) it is better to fix in just one
place, the generator of the problematic types.

Signed-off-by: Francisco Javier Tirado Sarti <ftirados@ibm.com>

Author: fjtirado

api/src/test/java/io/serverlessworkflow/api/FeaturesTest.java

@@ -15,7 +15,6 @@
  */
 package io.serverlessworkflow.api;
 
-import static io.serverlessworkflow.api.WorkflowReader.readWorkflow;
 import static io.serverlessworkflow.api.WorkflowReader.readWorkflowFromClasspath;
 import static io.serverlessworkflow.api.WorkflowReader.validation;
 import static io.serverlessworkflow.api.WorkflowWriter.workflowAsBytes;
@@ -30,9 +29,13 @@
 import java.io.IOException;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class FeaturesTest {
 
+  private static final Logger logger = LoggerFactory.getLogger(FeaturesTest.class);
+
   @ParameterizedTest
   @ValueSource(
       strings = {
@@ -71,8 +74,11 @@ private static Workflow writeAndReadInMemory(Workflow workflow) throws IOExcepti
       writeWorkflow(out, workflow, WorkflowFormat.JSON);
       bytes = out.toByteArray();
     }
+    if (logger.isDebugEnabled()) {
+      logger.debug("Workflow string representation is {}", new String(bytes));
+    }
     try (ByteArrayInputStream in = new ByteArrayInputStream(bytes)) {
-      return readWorkflow(in, WorkflowFormat.JSON);
+      return validation().read(in, WorkflowFormat.JSON);
     }
   }
 

generators/types/src/main/java/io/serverlessworkflow/generator/CustomAnnotator.java

@@ -17,6 +17,7 @@
 
 import com.fasterxml.jackson.databind.JsonNode;
 import com.sun.codemodel.JDefinedClass;
+import com.sun.codemodel.JExpr;
 import com.sun.codemodel.JFieldVar;
 import io.serverlessworkflow.annotations.AdditionalProperties;
 import jakarta.validation.constraints.Pattern;
@@ -40,7 +41,9 @@ public void additionalPropertiesField(JFieldVar field, JDefinedClass clazz, Stri
   public void propertyField(
       JFieldVar field, JDefinedClass clazz, String propertyName, JsonNode propertyNode) {
     if (propertyNode.has(CONST)) {
-      field.annotate(Pattern.class).param("regexp", propertyNode.get(CONST).asText());
+      String callValue = propertyNode.get(CONST).asText();
+      field.annotate(Pattern.class).param("regexp", callValue);
+      field.init(JExpr.lit(callValue));
     }
   }
 }