Updating Java Nexus docs with testing samples (#4347)

* Updating Java Nexus docs with testing samples

* Adding snippets

---------

Co-authored-by: Jwahir Sundai <jwahir.sundai@temporal.io>

Author: Evanthx

docs/develop/java/nexus/feature-guide.mdx

@@ -97,10 +97,10 @@ In a polyglot environment, that is where more than one language and SDK is being
 This example uses Java classes serialized into JSON.
 
 <!--SNIPSTART samples-java-nexus-service-->
-[core/src/main/java/io/temporal/samples/nexus/service/NexusService.java](https://github.com/temporalio/samples-java/blob/nexus-snip-sync/core/src/main/java/io/temporal/samples/nexus/service/NexusService.java)
+[core/src/main/java/io/temporal/samples/nexus/service/SampleNexusService.java](https://github.com/temporalio/samples-java/blob/nexus-snip-sync/core/src/main/java/io/temporal/samples/nexus/service/SampleNexusService.java)
 ```java
 @Service
-public interface NexusService {
+public interface SampleNexusService {
   enum Language {
     EN,
     FR,
@@ -204,23 +204,23 @@ Use `Nexus.getOperationContext().getWorkflowClient(ctx)` to get the Temporal Cli
 Implementations can also make other calls, but handlers should be reliable to avoid tripping the [circuit breaker](/nexus/operations#circuit-breaking).
 
 {/* SNIPSTART samples-java-nexus-handler {"selectedLines": ["1-16", "43"]} */}
-[core/src/main/java/io/temporal/samples/nexus/handler/NexusServiceImpl.java](https://github.com/temporalio/samples-java/blob/nexus-snip-sync/core/src/main/java/io/temporal/samples/nexus/handler/NexusServiceImpl.java)
+[core/src/main/java/io/temporal/samples/nexus/handler/SampleNexusServiceImpl.java](https://github.com/temporalio/samples-java/blob/nexus-snip-sync/core/src/main/java/io/temporal/samples/nexus/handler/SampleNexusServiceImpl.java)
 ```java
 // To create a service implementation, annotate the class with @ServiceImpl and provide the
 // interface that the service implements. The service implementation class should have methods that
 // return OperationHandler that correspond to the operations defined in the service interface.
-@ServiceImpl(service = NexusService.class)
-public class NexusServiceImpl {
+@ServiceImpl(service = SampleNexusService.class)
+public class SampleNexusServiceImpl {
   @OperationImpl
-  public OperationHandler<NexusService.EchoInput, NexusService.EchoOutput> echo() {
+  public OperationHandler<SampleNexusService.EchoInput, SampleNexusService.EchoOutput> echo() {
     // OperationHandler.sync is a meant for exposing simple RPC handlers.
     return OperationHandler.sync(
         // The method is for making arbitrary short calls to other services or databases, or
         // perform simple computations such as this one. Users can also access a workflow client by
         // calling
         // Nexus.getOperationContext().getWorkflowClient(ctx) to make arbitrary calls such as
         // signaling, querying, or listing workflows.
-        (ctx, details, input) -> new NexusService.EchoOutput(input.getMessage()));
+        (ctx, details, input) -> new SampleNexusService.EchoOutput(input.getMessage()));
   }
 // ...
 }
@@ -238,16 +238,16 @@ All calls must complete within the [Nexus request timeout](/cloud/limits#nexus-o
 Use the `WorkflowRunOperation.fromWorkflowMethod` method, which is the easiest way to expose a Workflow as an operation.
 
 <!--SNIPSTART samples-java-nexus-handler {"selectedLines": ["1-5", "18-40"]}-->
-[core/src/main/java/io/temporal/samples/nexus/handler/NexusServiceImpl.java](https://github.com/temporalio/samples-java/blob/nexus-snip-sync/core/src/main/java/io/temporal/samples/nexus/handler/NexusServiceImpl.java)
+[core/src/main/java/io/temporal/samples/nexus/handler/SampleNexusServiceImpl.java](https://github.com/temporalio/samples-java/blob/nexus-snip-sync/core/src/main/java/io/temporal/samples/nexus/handler/SampleNexusServiceImpl.java)
 ```java
 // To create a service implementation, annotate the class with @ServiceImpl and provide the
 // interface that the service implements. The service implementation class should have methods that
 // return OperationHandler that correspond to the operations defined in the service interface.
-@ServiceImpl(service = NexusService.class)
-public class NexusServiceImpl {
+@ServiceImpl(service = SampleNexusService.class)
+public class SampleNexusServiceImpl {
 // ...
   @OperationImpl
-  public OperationHandler<NexusService.HelloInput, NexusService.HelloOutput> hello() {
+  public OperationHandler<SampleNexusService.HelloInput, SampleNexusService.HelloOutput> hello() {
     // Use the WorkflowRunOperation.fromWorkflowMethod constructor, which is the easiest
     // way to expose a workflow as an operation. To expose a workflow with a different input
     // parameters then the operation or from an untyped stub, use the
@@ -285,27 +285,27 @@ Workflow IDs should typically be business-meaningful IDs and are used to dedupe
 A Nexus Operation can only take one input parameter. If you want a Nexus Operation to start a Workflow that takes multiple arguments use the `WorkflowRunOperation.fromWorkflowHandle` method.
 
 <!--SNIPSTART samples-java-nexus-handler-multiargs-->
-[core/src/main/java/io/temporal/samples/nexusmultipleargs/handler/NexusServiceImpl.java](https://github.com/temporalio/samples-java/blob/nexus-snip-sync/core/src/main/java/io/temporal/samples/nexusmultipleargs/handler/NexusServiceImpl.java)
+[core/src/main/java/io/temporal/samples/nexusmultipleargs/handler/SampleNexusServiceImpl.java](https://github.com/temporalio/samples-java/blob/nexus-snip-sync/core/src/main/java/io/temporal/samples/nexusmultipleargs/handler/SampleNexusServiceImpl.java)
 ```java
 // To create a service implementation, annotate the class with @ServiceImpl and provide the
 // interface that the service implements. The service implementation class should have methods that
 // return OperationHandler that correspond to the operations defined in the service interface.
-@ServiceImpl(service = NexusService.class)
-public class NexusServiceImpl {
+@ServiceImpl(service = SampleNexusService.class)
+public class SampleNexusServiceImpl {
   @OperationImpl
-  public OperationHandler<NexusService.EchoInput, NexusService.EchoOutput> echo() {
+  public OperationHandler<SampleNexusService.EchoInput, SampleNexusService.EchoOutput> echo() {
     // OperationHandler.sync is a meant for exposing simple RPC handlers.
     return OperationHandler.sync(
         // The method is for making arbitrary short calls to other services or databases, or
         // perform simple computations such as this one. Users can also access a workflow client by
         // calling
         // Nexus.getOperationContext().getWorkflowClient(ctx) to make arbitrary calls such as
         // signaling, querying, or listing workflows.
-        (ctx, details, input) -> new NexusService.EchoOutput(input.getMessage()));
+        (ctx, details, input) -> new SampleNexusService.EchoOutput(input.getMessage()));
   }
 
   @OperationImpl
-  public OperationHandler<NexusService.HelloInput, NexusService.HelloOutput> hello() {
+  public OperationHandler<SampleNexusService.HelloInput, SampleNexusService.HelloOutput> hello() {
     // If the operation input parameters are different from the workflow input parameters,
     // use the WorkflowRunOperation.fromWorkflowHandler constructor and the appropriate constructor
     // method on WorkflowHandle to map the Nexus input to the workflow parameters.
@@ -363,7 +363,7 @@ public class HandlerWorker {
 
     Worker worker = factory.newWorker(DEFAULT_TASK_QUEUE_NAME);
     worker.registerWorkflowImplementationTypes(HelloHandlerWorkflowImpl.class);
-    worker.registerNexusServiceImplementation(new NexusServiceImpl());
+    worker.registerNexusServiceImplementation(new SampleNexusServiceImpl());
 
     factory.start();
   }
@@ -380,16 +380,16 @@ Import the Service API package that has the necessary service and operation name
 ```java
 package io.temporal.samples.nexus.caller;
 
-import io.temporal.samples.nexus.service.NexusService;
+import io.temporal.samples.nexus.service.SampleNexusService;
 import io.temporal.workflow.NexusOperationOptions;
 import io.temporal.workflow.NexusServiceOptions;
 import io.temporal.workflow.Workflow;
 import java.time.Duration;
 
 public class EchoCallerWorkflowImpl implements EchoCallerWorkflow {
-  NexusService nexusService =
+  SampleNexusService sampleNexusService =
       Workflow.newNexusServiceStub(
-          NexusService.class,
+          SampleNexusService.class,
           NexusServiceOptions.newBuilder()
               .setOperationOptions(
                   NexusOperationOptions.newBuilder()
@@ -399,7 +399,7 @@ public class EchoCallerWorkflowImpl implements EchoCallerWorkflow {
 
   @Override
   public String echo(String message) {
-    return nexusService.echo(new NexusService.EchoInput(message)).getMessage();
+    return sampleNexusService.echo(new SampleNexusService.EchoInput(message)).getMessage();
   }
 }
 ```
@@ -410,17 +410,17 @@ public class EchoCallerWorkflowImpl implements EchoCallerWorkflow {
 ```java
 package io.temporal.samples.nexus.caller;
 
-import io.temporal.samples.nexus.service.NexusService;
+import io.temporal.samples.nexus.service.SampleNexusService;
 import io.temporal.workflow.NexusOperationHandle;
 import io.temporal.workflow.NexusOperationOptions;
 import io.temporal.workflow.NexusServiceOptions;
 import io.temporal.workflow.Workflow;
 import java.time.Duration;
 
 public class HelloCallerWorkflowImpl implements HelloCallerWorkflow {
-  NexusService nexusService =
+  SampleNexusService sampleNexusService =
       Workflow.newNexusServiceStub(
-          NexusService.class,
+          SampleNexusService.class,
           NexusServiceOptions.newBuilder()
               .setOperationOptions(
                   NexusOperationOptions.newBuilder()
@@ -429,10 +429,10 @@ public class HelloCallerWorkflowImpl implements HelloCallerWorkflow {
               .build());
 
   @Override
-  public String hello(String message, NexusService.Language language) {
-    NexusOperationHandle<NexusService.HelloOutput> handle =
+  public String hello(String message, SampleNexusService.Language language) {
+    NexusOperationHandle<SampleNexusService.HelloOutput> handle =
         Workflow.startNexusOperation(
-            nexusService::hello, new NexusService.HelloInput(message, language));
+            sampleNexusService::hello, new SampleNexusService.HelloInput(message, language));
     // Optionally wait for the operation to be started. NexusOperationExecution will contain the
     // operation token in case this operation is asynchronous.
     handle.getExecution().get();
@@ -472,7 +472,7 @@ public class CallerWorker {
         WorkflowImplementationOptions.newBuilder()
             .setNexusServiceOptions(
                 Collections.singletonMap(
-                    "NexusService",
+                    "SampleNexusService",
                     NexusServiceOptions.newBuilder().setEndpoint("my-nexus-endpoint-name").build()))
             .build(),
         EchoCallerWorkflowImpl.class,
@@ -497,7 +497,7 @@ import io.temporal.api.common.v1.WorkflowExecution;
 import io.temporal.client.WorkflowClient;
 import io.temporal.client.WorkflowOptions;
 import io.temporal.samples.nexus.options.ClientOptions;
-import io.temporal.samples.nexus.service.NexusService;
+import io.temporal.samples.nexus.service.SampleNexusService;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -519,12 +519,12 @@ public class CallerStarter {
     logger.info("Workflow result: {}", echoWorkflow.echo("Nexus Echo 👋"));
     HelloCallerWorkflow helloWorkflow =
         client.newWorkflowStub(HelloCallerWorkflow.class, workflowOptions);
-    execution = WorkflowClient.start(helloWorkflow::hello, "Nexus", NexusService.Language.EN);
+    execution = WorkflowClient.start(helloWorkflow::hello, "Nexus", SampleNexusService.Language.EN);
     logger.info(
         "Started HelloCallerWorkflow workflowId: {} runId: {}",
         execution.getWorkflowId(),
         execution.getRunId());
-    logger.info("Workflow result: {}", helloWorkflow.hello("Nexus", NexusService.Language.ES));
+    logger.info("Workflow result: {}", helloWorkflow.hello("Nexus", SampleNexusService.Language.ES));
   }
 }
 ```