diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
index c44e070fe62..4b878c40e6c 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
@@ -229,6 +229,11 @@ public class DefaultCodegen {
     }
 
     public String toOperationId(String operationId) {
+        // throw exception if method name is empty
+        if (StringUtils.isEmpty(operationId)) {
+            throw new RuntimeException("Empty method name (operationId) not allowed");
+        }
+
         return operationId;
     }
 
@@ -1216,7 +1221,9 @@ public class DefaultCodegen {
         if (mappedType != null) {
             addImport(m, mappedType);
         }
-    }    /**
+    }
+
+    /**
      * Underscore the given word.
      *
      * @param word The word
@@ -1278,9 +1285,8 @@ public class DefaultCodegen {
         } else {
             m.emptyVars = true;
         }
-    }    public static String camelize(String word) {
-        return camelize(word, false);
     }
+    
 
     /**
      * Remove characters not suitable for variable or method name from the input and camelize it
@@ -1301,7 +1307,13 @@ public class DefaultCodegen {
             name = name.substring(0, 1).toLowerCase() + name.substring(1);
         }
         return name;
-    }    public static String camelize(String word, boolean lowercaseFirstLetter) {
+    }    
+
+    public static String camelize(String word) {
+        return camelize(word, false);
+    }
+
+    public static String camelize(String word, boolean lowercaseFirstLetter) {
         // Replace all slashes with dots (package separator)
         Pattern p = Pattern.compile("\\/(.?)");
         Matcher m = p.matcher(word);
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AkkaScalaClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AkkaScalaClientCodegen.java
index efcd771ac10..f9490e3d3dd 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AkkaScalaClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AkkaScalaClientCodegen.java
@@ -251,6 +251,11 @@ public class AkkaScalaClientCodegen extends DefaultCodegen implements CodegenCon
 
     @Override
     public String toOperationId(String operationId) {
+        // throw exception if method name is empty
+        if (StringUtils.isEmpty(operationId)) {
+            throw new RuntimeException("Empty method name (operationId) not allowed");
+        }
+
         return super.toOperationId(CaseFormat.UPPER_CAMEL.to(CaseFormat.LOWER_CAMEL, operationId));
     }
 
@@ -396,4 +401,4 @@ public class AkkaScalaClientCodegen extends DefaultCodegen implements CodegenCon
         }
     }
 
-}
\ No newline at end of file
+}
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AndroidClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AndroidClientCodegen.java
index e65736a63f0..f570cc42e82 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AndroidClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AndroidClientCodegen.java
@@ -13,6 +13,8 @@ import java.io.File;
 import java.util.Arrays;
 import java.util.HashSet;
 
+import org.apache.commons.lang.StringUtils;
+
 public class AndroidClientCodegen extends DefaultCodegen implements CodegenConfig {
     protected String invokerPackage = "io.swagger.client";
     protected String groupId = "io.swagger";
@@ -168,6 +170,11 @@ public class AndroidClientCodegen extends DefaultCodegen implements CodegenConfi
 
     @Override
     public String toOperationId(String operationId) {
+        // throw exception if method name is empty
+        if (StringUtils.isEmpty(operationId)) {
+            throw new RuntimeException("Empty method name (operationId) not allowed");
+        }
+
         // method name cannot use reserved keyword, e.g. return
         if (reservedWords.contains(operationId)) {
             throw new RuntimeException(operationId + " (reserved word) cannot be used as method name");
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AsyncScalaClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AsyncScalaClientCodegen.java
index c941d8b8d97..53faf2f9e1f 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AsyncScalaClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AsyncScalaClientCodegen.java
@@ -21,6 +21,8 @@ import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
 
+import org.apache.commons.lang.StringUtils;
+
 public class AsyncScalaClientCodegen extends DefaultCodegen implements CodegenConfig {
     protected String invokerPackage = "io.swagger.client";
     protected String groupId = "io.swagger";
@@ -204,4 +206,4 @@ public class AsyncScalaClientCodegen extends DefaultCodegen implements CodegenCo
             return "null";
         }
     }
-}
\ No newline at end of file
+}
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/CSharpClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/CSharpClientCodegen.java
index 5833d7287cc..1d7accd3b27 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/CSharpClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/CSharpClientCodegen.java
@@ -14,6 +14,8 @@ import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
 
+import org.apache.commons.lang.StringUtils;
+
 public class CSharpClientCodegen extends DefaultCodegen implements CodegenConfig {
     protected String packageName = "IO.Swagger";
     protected String packageVersion = "1.0.0";
@@ -237,6 +239,11 @@ public class CSharpClientCodegen extends DefaultCodegen implements CodegenConfig
 
     @Override
     public String toOperationId(String operationId) {
+        // throw exception if method name is empty
+        if (StringUtils.isEmpty(operationId)) {
+            throw new RuntimeException("Empty method name (operationId) not allowed");
+        }
+
         // method name cannot use reserved keyword, e.g. return
         if (reservedWords.contains(operationId)) {
             throw new RuntimeException(operationId + " (reserved word) cannot be used as method name");
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/JavaClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/JavaClientCodegen.java
index f753e63f5f7..f272343a795 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/JavaClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/JavaClientCodegen.java
@@ -13,6 +13,8 @@ import java.io.File;
 import java.util.Arrays;
 import java.util.HashSet;
 
+import org.apache.commons.lang.StringUtils;
+
 public class JavaClientCodegen extends DefaultCodegen implements CodegenConfig {
     protected String invokerPackage = "io.swagger.client";
     protected String groupId = "io.swagger";
@@ -234,6 +236,11 @@ public class JavaClientCodegen extends DefaultCodegen implements CodegenConfig {
 
     @Override
     public String toOperationId(String operationId) {
+        // throw exception if method name is empty
+        if (StringUtils.isEmpty(operationId)) {
+            throw new RuntimeException("Empty method name (operationId) not allowed");
+        }
+
         // method name cannot use reserved keyword, e.g. return
         if (reservedWords.contains(operationId)) {
             throw new RuntimeException(operationId + " (reserved word) cannot be used as method name");
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/ObjcClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/ObjcClientCodegen.java
index 3e5edbc169f..887422cd490 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/ObjcClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/ObjcClientCodegen.java
@@ -16,6 +16,8 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Set;
 
+import org.apache.commons.lang.StringUtils;
+
 public class ObjcClientCodegen extends DefaultCodegen implements CodegenConfig {
     protected Set<String> foundationClasses = new HashSet<String>();
     protected String podName = "SwaggerClient";
@@ -358,6 +360,11 @@ public class ObjcClientCodegen extends DefaultCodegen implements CodegenConfig {
 
     @Override
     public String toOperationId(String operationId) {
+        // throw exception if method name is empty
+        if (StringUtils.isEmpty(operationId)) {
+            throw new RuntimeException("Empty method name (operationId) not allowed");
+        }
+
         // method name cannot use reserved keyword, e.g. return
         if (reservedWords.contains(operationId)) {
             throw new RuntimeException(operationId + " (reserved word) cannot be used as method name");
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PerlClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PerlClientCodegen.java
index 8c079973a1b..80f83bc2d10 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PerlClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PerlClientCodegen.java
@@ -9,11 +9,12 @@ import io.swagger.models.properties.MapProperty;
 import io.swagger.models.properties.Property;
 import io.swagger.codegen.CliOption;
 
-
 import java.io.File;
 import java.util.Arrays;
 import java.util.HashSet;
 
+import org.apache.commons.lang.StringUtils;
+
 public class PerlClientCodegen extends DefaultCodegen implements CodegenConfig {
     protected String moduleName = "SwaggerClient";
     protected String moduleVersion = "1.0.0";
@@ -213,6 +214,11 @@ public class PerlClientCodegen extends DefaultCodegen implements CodegenConfig {
 
     @Override
     public String toOperationId(String operationId) {
+        // throw exception if method name is empty
+        if (StringUtils.isEmpty(operationId)) {
+            throw new RuntimeException("Empty method name (operationId) not allowed");
+        }
+
         // method name cannot use reserved keyword, e.g. return
         if (reservedWords.contains(operationId)) {
             throw new RuntimeException(operationId + " (reserved word) cannot be used as method name");
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PhpClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PhpClientCodegen.java
index 188e5c76644..1b40cc0a30e 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PhpClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PhpClientCodegen.java
@@ -15,6 +15,8 @@ import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
 
+import org.apache.commons.lang.StringUtils;
+
 public class PhpClientCodegen extends DefaultCodegen implements CodegenConfig {
     protected String invokerPackage = "Swagger\\Client";
     protected String composerVendorName = "swagger";
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/Python3ClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/Python3ClientCodegen.java
index 71562e6ba37..70c090cd7a3 100755
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/Python3ClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/Python3ClientCodegen.java
@@ -12,6 +12,8 @@ import java.io.File;
 import java.util.Arrays;
 import java.util.HashSet;
 
+import org.apache.commons.lang.StringUtils;
+
 public class Python3ClientCodegen extends DefaultCodegen implements CodegenConfig {
     String module = "client";
 
@@ -201,6 +203,11 @@ public class Python3ClientCodegen extends DefaultCodegen implements CodegenConfi
 
     @Override
     public String toOperationId(String operationId) {
+        // throw exception if method name is empty
+        if (StringUtils.isEmpty(operationId)) {
+            throw new RuntimeException("Empty method name (operationId) not allowed");
+        }
+
         // method name cannot use reserved keyword, e.g. return
         if (reservedWords.contains(operationId)) {
             throw new RuntimeException(operationId + " (reserved word) cannot be used as method name");
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PythonClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PythonClientCodegen.java
index 8f78f2e1d49..e0e1bdc07f8 100755
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PythonClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PythonClientCodegen.java
@@ -13,6 +13,8 @@ import java.io.File;
 import java.util.Arrays;
 import java.util.HashSet;
 
+import org.apache.commons.lang.StringUtils;
+
 public class PythonClientCodegen extends DefaultCodegen implements CodegenConfig {
     protected String packageName = null;
     protected String packageVersion = null;
@@ -246,6 +248,11 @@ public class PythonClientCodegen extends DefaultCodegen implements CodegenConfig
 
     @Override
     public String toOperationId(String operationId) {
+        // throw exception if method name is empty
+        if (StringUtils.isEmpty(operationId)) {
+            throw new RuntimeException("Empty method name (operationId) not allowed");
+        }
+
         // method name cannot use reserved keyword, e.g. return
         if (reservedWords.contains(operationId)) {
             throw new RuntimeException(operationId + " (reserved word) cannot be used as method name");
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/RetrofitClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/RetrofitClientCodegen.java
index e043c68baf9..66d3f19f948 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/RetrofitClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/RetrofitClientCodegen.java
@@ -15,6 +15,8 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 
+import org.apache.commons.lang.StringUtils;
+
 public class RetrofitClientCodegen extends DefaultCodegen implements CodegenConfig {
     protected String invokerPackage = "io.swagger.client";
     protected String groupId = "io.swagger";
@@ -171,6 +173,11 @@ public class RetrofitClientCodegen extends DefaultCodegen implements CodegenConf
 
     @Override
     public String toOperationId(String operationId) {
+        // throw exception if method name is empty
+        if (StringUtils.isEmpty(operationId)) {
+            throw new RuntimeException("Empty method name (operationId) not allowed");
+        }
+
         // method name cannot use reserved keyword, e.g. return
         if (reservedWords.contains(operationId)) {
             throw new RuntimeException(operationId + " (reserved word) cannot be used as method name");
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/RubyClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/RubyClientCodegen.java
index 716c1bb0870..36a3f31aa48 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/RubyClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/RubyClientCodegen.java
@@ -13,6 +13,8 @@ import java.io.File;
 import java.util.Arrays;
 import java.util.HashSet;
 
+import org.apache.commons.lang.StringUtils;
+
 public class RubyClientCodegen extends DefaultCodegen implements CodegenConfig {
     protected String gemName = null;
     protected String moduleName = null;
@@ -267,6 +269,11 @@ public class RubyClientCodegen extends DefaultCodegen implements CodegenConfig {
 
     @Override
     public String toOperationId(String operationId) {
+        // throw exception if method name is empty
+        if (StringUtils.isEmpty(operationId)) {
+            throw new RuntimeException("Empty method name (operationId) not allowed");
+        }
+
         // method name cannot use reserved keyword, e.g. return
         if (reservedWords.contains(operationId)) {
             throw new RuntimeException(operationId + " (reserved word) cannot be used as method name");
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/ScalaClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/ScalaClientCodegen.java
index 6ad296a0210..5d8ae4b89b6 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/ScalaClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/ScalaClientCodegen.java
@@ -24,6 +24,8 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 
+import org.apache.commons.lang.StringUtils;
+
 public class ScalaClientCodegen extends DefaultCodegen implements CodegenConfig {
     protected String invokerPackage = "io.swagger.client";
     protected String groupId = "io.swagger";
@@ -209,6 +211,11 @@ public class ScalaClientCodegen extends DefaultCodegen implements CodegenConfig
 
     @Override
     public String toOperationId(String operationId) {
+        // throw exception if method name is empty
+        if (StringUtils.isEmpty(operationId)) {
+            throw new RuntimeException("Empty method name (operationId) not allowed");
+        }
+
         // method name cannot use reserved keyword, e.g. return
         if (reservedWords.contains(operationId)) {
             throw new RuntimeException(operationId + " (reserved word) cannot be used as method name");
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/SinatraServerCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/SinatraServerCodegen.java
index 44cf978eb1d..5bc402fe0c4 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/SinatraServerCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/SinatraServerCodegen.java
@@ -13,6 +13,8 @@ import java.io.File;
 import java.util.Arrays;
 import java.util.HashSet;
 
+import org.apache.commons.lang.StringUtils;
+
 public class SinatraServerCodegen extends DefaultCodegen implements CodegenConfig {
     protected String gemName = null;
     protected String moduleName = null;
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/TizenClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/TizenClientCodegen.java
index 34305d7c56f..7dc0b8ec3bd 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/TizenClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/TizenClientCodegen.java
@@ -25,6 +25,8 @@ import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 
+import org.apache.commons.lang.StringUtils;
+
 public class TizenClientCodegen extends DefaultCodegen implements CodegenConfig {
     protected static String PREFIX = "Sami";
     protected Set<String> foundationClasses = new HashSet<String>();
@@ -265,6 +267,11 @@ public class TizenClientCodegen extends DefaultCodegen implements CodegenConfig
 
     @Override
     public String toOperationId(String operationId) {
+        // throw exception if method name is empty
+        if (StringUtils.isEmpty(operationId)) {
+            throw new RuntimeException("Empty method name (operationId) not allowed");
+        }
+
         // method name cannot use reserved keyword, e.g. return$
         if (reservedWords.contains(operationId)) {
             throw new RuntimeException(operationId + " (reserved word) cannot be used as method name");
diff --git a/samples/client/petstore/java/src/main/java/io/swagger/client/model/Pet.java b/samples/client/petstore/java/src/main/java/io/swagger/client/model/Pet.java
index cf7ace02309..d7c2038dead 100644
--- a/samples/client/petstore/java/src/main/java/io/swagger/client/model/Pet.java
+++ b/samples/client/petstore/java/src/main/java/io/swagger/client/model/Pet.java
@@ -14,8 +14,8 @@ public class Pet  {
   private Long id = null;
   private Category category = null;
   private String name = null;
-  private List<String> photoUrls = new ArrayList<String>() ;
-  private List<Tag> tags = new ArrayList<Tag>() ;
+  private List<String> photoUrls = new ArrayList<String>();
+  private List<Tag> tags = new ArrayList<Tag>();
   public enum StatusEnum {
      available,  pending,  sold, 
   };