Hexagonal Architecture in Java - incorporated feedback

core-java-modules/core-java-lang-oop/src/main/java/com/baeldung/hexagon/ConstantTaxRateRepository.java

@@ -1,7 +1,6 @@
 package com.baeldung.hexagon;
 
 public class ConstantTaxRateRepository implements TaxRateRepository {
-
     private static final double TAX_RATE = 0.13d;
 
     @Override

core-java-modules/core-java-lang-oop/src/main/java/com/baeldung/hexagon/TaxCalculator.java

@@ -10,8 +10,7 @@ public class TaxCalculator implements TaxService {
     }
 
     @Override
-	public double calculateTax(Double amount) {
+    public double calculateTax(double amount) {
         return amount * taxRateRepository.getRate();
     }
-	
 }

core-java-modules/core-java-lang-oop/src/main/java/com/baeldung/hexagon/TaxFactory.java

@@ -1,7 +1,6 @@
 package com.baeldung.hexagon;
 
 public class TaxFactory {
-	
     public static TaxService getTaxService() {
         return new TaxCalculator(getTaxRepository());
     }
@@ -9,5 +8,4 @@ public class TaxFactory {
     public static TaxRateRepository getTaxRepository() {
         return new ConstantTaxRateRepository();
     }
-
 }

core-java-modules/core-java-lang-oop/src/main/java/com/baeldung/hexagon/TaxRateRepository.java

@@ -1,6 +1,5 @@
 package com.baeldung.hexagon;
 
 public interface TaxRateRepository {
-
     public double getRate();
 }

core-java-modules/core-java-lang-oop/src/main/java/com/baeldung/hexagon/TaxService.java

@@ -1,7 +1,5 @@
 package com.baeldung.hexagon;
 
 public interface TaxService {
-
-	public double calculateTax(Double amount);
-	
+    public double calculateTax(double amount);
 }

core-java-modules/core-java-lang-oop/src/main/java/com/baeldung/hexagon/TestTaxUser.java

@@ -3,7 +3,7 @@ package com.baeldung.hexagon;
 public class TestTaxUser {
 
     public double calculateTax(Double amount) {
-		return TaxFactory.getTaxService().calculateTax(amount);
+        return TaxFactory.getTaxService()
+            .calculateTax(amount);
     }
-
 }