diff --git a/generator/build.gradle.kts b/generator/build.gradle.kts
index ed78005..1c26ab7 100644
--- a/generator/build.gradle.kts
+++ b/generator/build.gradle.kts
@@ -79,6 +79,7 @@ dependencies {
     implementation("com.google.protobuf:protobuf-java:3.21.9")
     implementation("com.fasterxml.jackson.dataformat:jackson-dataformat-yaml:2.15.2")
 
+    implementation("one.util:streamex:0.8.2")
     implementation("org.apache.commons:commons-lang3:3.13.0")
     implementation("commons-io:commons-io:2.13.0")
 }
diff --git a/generator/src/main/java/org/sudu/protogen/generator/field/FieldGenerator.java b/generator/src/main/java/org/sudu/protogen/generator/field/FieldGenerator.java
index b01b295..66a8021 100644
--- a/generator/src/main/java/org/sudu/protogen/generator/field/FieldGenerator.java
+++ b/generator/src/main/java/org/sudu/protogen/generator/field/FieldGenerator.java
@@ -7,6 +7,9 @@
 import org.sudu.protogen.generator.type.TypeModel;
 import org.sudu.protogen.utils.Poem;
 
+import java.util.Collection;
+import java.util.stream.Stream;
+
 public class FieldGenerator {
 
     private final GenerationContext context;
@@ -18,6 +21,12 @@ public FieldGenerator(GenerationContext context, Field field) {
         this.field = field;
     }
 
+    public static Stream<FieldProcessingResult> generateSeveral(Collection<Field> fields, GenerationContext context) {
+        return fields.stream()
+                .map(field -> new FieldGenerator(context, field).generate())
+                .filter(FieldProcessingResult::isNonVoid);
+    }
+
     @NotNull
     public FieldProcessingResult generate() {
         if (field.isIgnored()) {
diff --git a/generator/src/main/java/org/sudu/protogen/generator/server/AbstractServiceMethodGenerator.java b/generator/src/main/java/org/sudu/protogen/generator/server/AbstractServiceMethodGenerator.java
index e347f95..d001e74 100644
--- a/generator/src/main/java/org/sudu/protogen/generator/server/AbstractServiceMethodGenerator.java
+++ b/generator/src/main/java/org/sudu/protogen/generator/server/AbstractServiceMethodGenerator.java
@@ -1,6 +1,7 @@
 package org.sudu.protogen.generator.server;
 
 import com.squareup.javapoet.*;
+import one.util.streamex.StreamEx;
 import org.jetbrains.annotations.Nullable;
 import org.sudu.protogen.descriptors.Method;
 import org.sudu.protogen.generator.GenerationContext;
@@ -84,13 +85,9 @@ private Iterable<ParameterSpec> generateMethodParameters() {
                 ).filter(Objects::nonNull).toList();
             }
         }
-        return Stream.concat(
-                method.getInputType().getFields().stream()
-                        .map(f -> new FieldGenerator(context, f).generate())
-                        .filter(FieldProcessingResult::isNonVoid)
-                        .map(FieldProcessingResult::field)
-                        .map(Poem::fieldToParameter),
-                Stream.of(generateObserverParameter())
-        ).filter(Objects::nonNull).toList();
+        Stream<ParameterSpec> unfoldedFields = FieldGenerator.generateSeveral(method.getInputType().getFields(), context)
+                .map(FieldProcessingResult::field)
+                .map(Poem::fieldToParameter);
+        return StreamEx.of(unfoldedFields).append(generateObserverParameter()).nonNull().toList();
     }
 }
diff --git a/generator/src/main/java/org/sudu/protogen/generator/server/OverriddenServiceMethodGenerator.java b/generator/src/main/java/org/sudu/protogen/generator/server/OverriddenServiceMethodGenerator.java
index 751e91d..d82e71c 100644
--- a/generator/src/main/java/org/sudu/protogen/generator/server/OverriddenServiceMethodGenerator.java
+++ b/generator/src/main/java/org/sudu/protogen/generator/server/OverriddenServiceMethodGenerator.java
@@ -1,11 +1,11 @@
 package org.sudu.protogen.generator.server;
 
 import com.squareup.javapoet.*;
+import one.util.streamex.StreamEx;
 import org.jetbrains.annotations.Nullable;
 import org.sudu.protogen.descriptors.Method;
 import org.sudu.protogen.generator.GenerationContext;
 import org.sudu.protogen.generator.field.FieldGenerator;
-import org.sudu.protogen.generator.field.FieldProcessingResult;
 import org.sudu.protogen.generator.message.FieldTransformerGenerator;
 import org.sudu.protogen.generator.type.TypeModel;
 import org.sudu.protogen.generator.type.UnfoldedType;
@@ -13,7 +13,6 @@
 
 import javax.lang.model.element.Modifier;
 import java.util.List;
-import java.util.stream.Stream;
 
 /**
  * Overrides default stub method to pass request and response as domain objects or list of fields
@@ -82,24 +81,22 @@ private CodeBlock generateAbstractMethodCallParams() {
         if (requestType != null && !method.doUnfoldRequest()) {
             return CodeBlock.of("$L",
                     Poem.separatedSequence(
-                            Stream.concat(
-                                    Stream.of(requestType.fromGrpcTransformer(CodeBlock.of("request"))),
-                                    generateResponseObserver().stream()
-                            ).toList(),
+                            StreamEx.of(requestType.fromGrpcTransformer(CodeBlock.of("request")))
+                                    .append(generateResponseObserver())
+                                    .toList(),
                             ",\n"
                     )
             );
         }
         // todo think about how to took out such logic because client does the same
-        List<CodeBlock> unfoldedRequestFields = method.getInputType().getFields().stream()
-                .map(field -> new FieldGenerator(context, field).generate())
-                .filter(FieldProcessingResult::isNonVoid)
+        List<CodeBlock> unfoldedRequestFields = FieldGenerator.generateSeveral(method.getInputType().getFields(), context)
                 .map(f -> new FieldTransformerGenerator(f.type(), f.original().getName(), f.isNullable())
-                        .fromGrpc("request"))
-                .toList();
-        return CodeBlock.of("$L",
-                Poem.separatedSequence(Stream.concat(unfoldedRequestFields.stream(), generateResponseObserver().stream()).toList(), ",\n")
-        );
+                        .fromGrpc("request")
+                ).toList();
+        return CodeBlock.of("$L", Poem.separatedSequence(
+                StreamEx.of(unfoldedRequestFields).append(generateResponseObserver()).toList(),
+                ",\n"
+        ));
     }
 
     /**
@@ -115,12 +112,12 @@ private List<CodeBlock> generateResponseObserver() {
         }
         if (method.doUnfoldResponse()) {
             var field = method.unfoldedResponseField();
-            TypeModel type = context.processType(field);
-            return List.of(CodeBlock.of(
-                    "$L", new AnonymousStreamObserverGenerator(
-                            new UnfoldedType(type, field.getName(), method.getOutputType().getProtobufTypeName())
-                    ).generate()
-            ));
+            TypeModel type = new UnfoldedType(
+                    context.processType(field),
+                    field.getName(),
+                    method.getOutputType().getProtobufTypeName()
+            );
+            return List.of(CodeBlock.of("$L", new AnonymousStreamObserverGenerator(type).generate()));
         }
         return List.of(CodeBlock.of("responseObserver"));
     }
@@ -131,7 +128,7 @@ private List<CodeBlock> generateResponseObserver() {
      * {@code GrpcSomeRequest request, StreamObserver<GrpcSomeResponse> response}
      * </pre>
      */
-    private Iterable<ParameterSpec> generateMethodParameters() {
+    private List<ParameterSpec> generateMethodParameters() {
         TypeName requestType = method.getInputType().getProtobufTypeName();
         TypeName responseType = method.getOutputType().getProtobufTypeName();
         ParameterizedTypeName responseObserverType = ParameterizedTypeName.get(