diff --git a/packages/http-client-java/emitter/src/code-model-builder.ts b/packages/http-client-java/emitter/src/code-model-builder.ts
index 042e0ec1e4..a6b4255009 100644
--- a/packages/http-client-java/emitter/src/code-model-builder.ts
+++ b/packages/http-client-java/emitter/src/code-model-builder.ts
@@ -199,13 +199,12 @@ export class CodeModelBuilder {
     }
 
     const service = listServices(this.program)[0];
-    const serviceNamespace = service.type;
-    if (serviceNamespace === undefined) {
-      throw Error("Cannot emit yaml for a namespace that doesn't exist.");
+    if (!service) {
+      throw Error("TypeSpec for HTTP must define a service.");
     }
-    this.serviceNamespace = serviceNamespace;
+    this.serviceNamespace = service.type;
 
-    this.namespace = getNamespaceFullName(serviceNamespace) || "Azure.Client";
+    this.namespace = getNamespaceFullName(this.serviceNamespace) || "Azure.Client";
     // java namespace
     const javaNamespace = this.getJavaNamespace(this.namespace);
 
@@ -219,9 +218,9 @@ export class CodeModelBuilder {
     };
 
     // init code model
-    const title = this.options["service-name"] ?? serviceNamespace.name;
+    const title = this.options["service-name"] ?? this.serviceNamespace.name;
 
-    const description = this.getDoc(serviceNamespace);
+    const description = this.getDoc(this.serviceNamespace);
     this.codeModel = new CodeModel(title, false, {
       info: {
         description: description,
@@ -230,7 +229,7 @@ export class CodeModelBuilder {
         default: {
           name: title,
           description: description,
-          summary: this.getSummary(serviceNamespace),
+          summary: this.getSummary(this.serviceNamespace),
           namespace: this.namespace,
         },
         java: {
diff --git a/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/mapper/ClientMapper.java b/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/mapper/ClientMapper.java
index ff3eb439db..55bc9fa0f5 100644
--- a/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/mapper/ClientMapper.java
+++ b/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/mapper/ClientMapper.java
@@ -192,9 +192,11 @@ public Client map(CodeModel codeModel) {
             } else {
                 // service client
                 ServiceClient serviceClient = Mappers.getServiceClientMapper().map(codeModel);
-                builder.serviceClient(serviceClient);
+                if (serviceClient != null) {
+                    builder.serviceClient(serviceClient);
 
-                serviceClientsMap.put(serviceClient, codeModel);
+                    serviceClientsMap.put(serviceClient, codeModel);
+                }
             }
         }
 
diff --git a/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/preprocessor/tranformer/Transformer.java b/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/preprocessor/tranformer/Transformer.java
index 578af267c6..852e1de31a 100644
--- a/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/preprocessor/tranformer/Transformer.java
+++ b/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/preprocessor/tranformer/Transformer.java
@@ -54,9 +54,16 @@ public CodeModel transform(CodeModel codeModel) {
       markFlattenedSchemas(codeModel);
     }
     transformOperationGroups(codeModel.getOperationGroups(), codeModel);
+    if (codeModel.getGlobalParameters() != null) {
+      for (Parameter parameter : codeModel.getGlobalParameters()) {
+        if (parameter.getLanguage().getJava() == null) {
+          renameVariable(parameter);
+        }
+      }
+    }
     // multi-clients for TypeSpec
     if (codeModel.getClients() != null) {
-      transformClients(codeModel.getClients(), codeModel);
+      transformClients(codeModel.getClients());
     }
     return codeModel;
   }
@@ -108,7 +115,7 @@ private void transformSchemas(Schemas schemas) {
     }
   }
 
-  private void transformClients(List<Client> clients, CodeModel codeModel) {
+  private void transformClients(List<Client> clients) {
     for (Client client : clients) {
       renameClient(client);
 
@@ -138,6 +145,14 @@ private void transformClients(List<Client> clients, CodeModel codeModel) {
           }
         }
       }
+
+      if (client.getGlobalParameters() != null) {
+        for (Parameter parameter : client.getGlobalParameters()) {
+          if (parameter.getLanguage().getJava() == null) {
+            renameVariable(parameter);
+          }
+        }
+      }
     }
   }
 
diff --git a/packages/http-client-java/generator/http-client-generator/src/main/java/com/microsoft/typespec/http/client/generator/mapper/TypeSpecClientMapper.java b/packages/http-client-java/generator/http-client-generator/src/main/java/com/microsoft/typespec/http/client/generator/mapper/TypeSpecClientMapper.java
index ffaf9f1559..60591302d9 100644
--- a/packages/http-client-java/generator/http-client-generator/src/main/java/com/microsoft/typespec/http/client/generator/mapper/TypeSpecClientMapper.java
+++ b/packages/http-client-java/generator/http-client-generator/src/main/java/com/microsoft/typespec/http/client/generator/mapper/TypeSpecClientMapper.java
@@ -35,7 +35,10 @@ protected Map<ServiceClient, Client> processClients(List<Client> clients, CodeMo
         Map<ServiceClient, Client> serviceClientsMap = new LinkedHashMap<>();
         TypeSpecServiceClientMapper mapper = new TypeSpecServiceClientMapper();
         for (Client client : clients) {
-            serviceClientsMap.put(mapper.map(client, codeModel), client);
+            ServiceClient serviceClient = mapper.map(client, codeModel);
+            if (serviceClient != null) {
+                serviceClientsMap.put(serviceClient, client);
+            }
         }
         return serviceClientsMap;
     }
diff --git a/packages/http-client-java/generator/http-client-generator/src/main/java/com/microsoft/typespec/http/client/generator/mapper/TypeSpecServiceClientMapper.java b/packages/http-client-java/generator/http-client-generator/src/main/java/com/microsoft/typespec/http/client/generator/mapper/TypeSpecServiceClientMapper.java
index eeecda393a..989ebc2be8 100644
--- a/packages/http-client-java/generator/http-client-generator/src/main/java/com/microsoft/typespec/http/client/generator/mapper/TypeSpecServiceClientMapper.java
+++ b/packages/http-client-java/generator/http-client-generator/src/main/java/com/microsoft/typespec/http/client/generator/mapper/TypeSpecServiceClientMapper.java
@@ -55,6 +55,11 @@ public ServiceClient map(Client client, CodeModel codeModel) {
                 .forEach(og -> methodGroupClients.add(Mappers.getMethodGroupMapper().map(og, properties)));
         builder.methodGroupClients(methodGroupClients);
 
+        if (proxy == null && CoreUtils.isNullOrEmpty(methodGroupClients)) {
+            // No operation in this client, and no operation group as well. Abort the processing.
+            return null;
+        }
+
         if (proxy == null) {
             proxy = methodGroupClients.iterator().next().getProxy();
         }