Add explicit void return type if set by user

Author: Legion2

src/main/java/io/outfoxx/typescriptpoet/FunctionSpec.kt

@@ -104,7 +104,7 @@ private constructor(
       codeWriter.emitCode("]")
     }
 
-    if (returnType != null && returnType != TypeName.VOID) {
+    if (returnType != null) {
       codeWriter.emitCode(CodeBlock.of(": %T", returnType))
     }
   }

src/test/java/io/outfoxx/typescriptpoet/test/FunctionSpecTests.kt

@@ -197,8 +197,8 @@ class FunctionSpecTests {
   }
 
   @Test
-  @DisplayName("Generates no return type when void")
-  fun testGenNoReturnTypeForVoid() {
+  @DisplayName("Generates return type when void")
+  fun testGenReturnTypeForVoid() {
     val testClass = FunctionSpec.builder("test")
       .returns(TypeName.VOID)
       .build()
@@ -210,7 +210,7 @@ class FunctionSpecTests {
       out.toString(),
       equalTo(
         """
-            function test() {
+            function test(): void {
             }
 
         """.trimIndent()