DiffOrder Implementation and throw discover exception.

Author: jonpereiradev

src/main/java/com/github/jonpereiradev/diffobjects/builder/DiffConfigurationImpl.java

@@ -1,17 +1,21 @@
 package com.github.jonpereiradev.diffobjects.builder;
 
+import com.github.jonpereiradev.diffobjects.annotation.DiffOrder;
 import com.github.jonpereiradev.diffobjects.strategy.DiffMetadata;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 
 final class DiffConfigurationImpl implements DiffConfiguration {
 
     private final Map<String, DiffMetadata> metadatas;
+    private final List<DiffMetadata> diffMetadatas;
 
     DiffConfigurationImpl(Map<String, DiffMetadata> metadatas) {
         this.metadatas = metadatas;
+        this.diffMetadatas = new ArrayList<>(metadatas.keySet().size());
     }
 
     /**
@@ -21,7 +25,26 @@ final class DiffConfigurationImpl implements DiffConfiguration {
      */
     @Override
     public List<DiffMetadata> build() {
-        return new ArrayList<>(metadatas.values());
+        if (diffMetadatas.isEmpty()) {
+            boolean isSortable = false;
+
+            for (Map.Entry<String, DiffMetadata> entry : metadatas.entrySet()) {
+                DiffOrder annotation = entry.getValue().getMethod().getAnnotation(DiffOrder.class);
+
+                if (annotation != null) {
+                    entry.getValue().setOrder(annotation.value());
+                    isSortable = true;
+                }
+
+                diffMetadatas.add(entry.getValue());
+            }
+
+            if (isSortable) {
+                Collections.sort(diffMetadatas);
+            }
+        }
+
+        return diffMetadatas;
     }
 
 }

src/main/java/com/github/jonpereiradev/diffobjects/builder/DiffMappingBuilderImpl.java

@@ -81,10 +81,6 @@ public DiffQueryBuilder mapping(String field, String value) {
         Method method = DiffReflections.discoverGetter(classMap, field);
         DiffStrategyType diffStrategyType = DiffStrategyType.SINGLE;
 
-        if (method == null) {
-            throw new DiffException("Method " + field + " not found in class " + classMap.getName());
-        }
-
         if (!Modifier.isPublic(method.getModifiers()) || method.getParameterTypes().length > 0) {
             throw new DiffException("Method " + method.getName() + " must be public and no-args.");
         }

src/main/java/com/github/jonpereiradev/diffobjects/strategy/DiffReflections.java

@@ -75,7 +75,13 @@ public static Method discoverGetter(Class<?> diffClass, String fieldOrMethodName
             possibleAccessMethodName = "get" + StringUtils.capitalize(fieldOrMethodName);
         }
 
-        return MethodUtils.getMatchingAccessibleMethod(diffClass, possibleAccessMethodName, null);
+        Method method = MethodUtils.getMatchingAccessibleMethod(diffClass, possibleAccessMethodName, null);
+
+        if (method == null) {
+            throw new DiffException("Method " + possibleAccessMethodName + " not found in class " + diffClass.getName());
+        }
+
+        return method;
     }
 
     /**