Drop special logics and annotation that indicates using java 8 and 7

Related with #1207

Author: kazuki43zoo

src/main/java/org/apache/ibatis/binding/MapperMethod.java

@@ -21,9 +21,7 @@
 import org.apache.ibatis.mapping.MappedStatement;
 import org.apache.ibatis.mapping.SqlCommandType;
 import org.apache.ibatis.mapping.StatementType;
-import org.apache.ibatis.reflection.Jdk;
 import org.apache.ibatis.reflection.MetaObject;
-import org.apache.ibatis.reflection.OptionalUtil;
 import org.apache.ibatis.reflection.ParamNameResolver;
 import org.apache.ibatis.reflection.TypeParameterResolver;
 import org.apache.ibatis.session.Configuration;
@@ -86,7 +84,7 @@ public Object execute(SqlSession sqlSession, Object[] args) {
           result = sqlSession.selectOne(command.getName(), param);
           if (method.returnsOptional() &&
               (result == null || !method.getReturnType().equals(result.getClass()))) {
-            result = OptionalUtil.ofNullable(result);
+            result = Optional.ofNullable(result);
           }
         }
         break;
@@ -296,7 +294,7 @@ public MethodSignature(Configuration configuration, Class<?> mapperInterface, Me
       this.returnsVoid = void.class.equals(this.returnType);
       this.returnsMany = configuration.getObjectFactory().isCollection(this.returnType) || this.returnType.isArray();
       this.returnsCursor = Cursor.class.equals(this.returnType);
-      this.returnsOptional = Jdk.optionalExists && Optional.class.equals(this.returnType);
+      this.returnsOptional = Optional.class.equals(this.returnType);
       this.mapKey = getMapKey(method);
       this.returnsMap = this.mapKey != null;
       this.rowBoundsIndex = getUniqueParamIndex(method, RowBounds.class);

src/main/java/org/apache/ibatis/binding/MapperProxy.java

@@ -23,7 +23,6 @@
 import java.lang.reflect.Modifier;
 import java.util.Map;
 
-import org.apache.ibatis.lang.UsesJava7;
 import org.apache.ibatis.reflection.ExceptionUtil;
 import org.apache.ibatis.session.SqlSession;
 
@@ -63,7 +62,6 @@ private MapperMethod cachedMapperMethod(Method method) {
     return methodCache.computeIfAbsent(method, k -> new MapperMethod(mapperInterface, method, sqlSession.getConfiguration()));
   }
 
-  @UsesJava7
   private Object invokeDefaultMethod(Object proxy, Method method, Object[] args)
       throws Throwable {
     final Constructor<MethodHandles.Lookup> constructor = MethodHandles.Lookup.class

src/main/java/org/apache/ibatis/builder/annotation/MapperAnnotationBuilder.java

@@ -81,7 +81,6 @@
 import org.apache.ibatis.mapping.SqlSource;
 import org.apache.ibatis.mapping.StatementType;
 import org.apache.ibatis.parsing.PropertyParser;
-import org.apache.ibatis.reflection.Jdk;
 import org.apache.ibatis.reflection.TypeParameterResolver;
 import org.apache.ibatis.scripting.LanguageDriver;
 import org.apache.ibatis.session.Configuration;
@@ -451,7 +450,7 @@ private Class<?> getReturnType(Method method) {
               returnType = (Class<?>) ((ParameterizedType) returnTypeParameter).getRawType();
             }
           }
-      } else if (Jdk.optionalExists && Optional.class.equals(rawType)) {
+      } else if (Optional.class.equals(rawType)) {
         Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
         Type returnTypeParameter = actualTypeArguments[0];
         if (returnTypeParameter instanceof Class<?>) {

src/main/java/org/apache/ibatis/mapping/ResultMap.java

@@ -28,7 +28,6 @@
 import org.apache.ibatis.builder.BuilderException;
 import org.apache.ibatis.logging.Log;
 import org.apache.ibatis.logging.LogFactory;
-import org.apache.ibatis.reflection.Jdk;
 import org.apache.ibatis.reflection.ParamNameUtil;
 import org.apache.ibatis.session.Configuration;
 
@@ -193,7 +192,7 @@ private List<String> getArgNames(Constructor<?> constructor) {
             break;
           }
         }
-        if (name == null && resultMap.configuration.isUseActualParamName() && Jdk.parameterExists) {
+        if (name == null && resultMap.configuration.isUseActualParamName()) {
           if (actualParamNames == null) {
             actualParamNames = ParamNameUtil.getParamNames(constructor);
           }

src/main/java/org/apache/ibatis/reflection/Jdk.java

@@ -24,7 +24,9 @@ public class Jdk {
 
   /**
    * <code>true</code> if <code>java.lang.reflect.Parameter</code> is available.
+   * @deprecated Since 3.5.0, Will remove this field at feature(next major version up)
    */
+  @Deprecated
   public static final boolean parameterExists;
 
   static {
@@ -38,6 +40,10 @@ public class Jdk {
     parameterExists = available;
   }
 
+  /**
+   * @deprecated Since 3.5.0, Will remove this field at feature(next major version up)
+   */
+  @Deprecated
   public static final boolean dateAndTimeApiExists;
 
   static {
@@ -51,6 +57,10 @@ public class Jdk {
     dateAndTimeApiExists = available;
   }
 
+  /**
+   * @deprecated Since 3.5.0, Will remove this field at feature(next major version up)
+   */
+  @Deprecated
   public static final boolean optionalExists;
 
   static {

src/main/java/org/apache/ibatis/reflection/OptionalUtil.java

@@ -18,11 +18,12 @@
 
 import java.util.Optional;
 
-import org.apache.ibatis.lang.UsesJava8;
-
+/**
+ * @deprecated Since 3.5.0, Will remove this class at future(next major version up).
+ */
+@Deprecated
 public abstract class OptionalUtil {
 
-  @UsesJava8
   public static Object ofNullable(Object value) {
     return Optional.ofNullable(value);
   }

src/main/java/org/apache/ibatis/reflection/ParamNameResolver.java

@@ -85,10 +85,7 @@ public ParamNameResolver(Configuration config, Method method) {
   }
 
   private String getActualParamName(Method method, int paramIndex) {
-    if (Jdk.parameterExists) {
-      return ParamNameUtil.getParamNames(method).get(paramIndex);
-    }
-    return null;
+    return ParamNameUtil.getParamNames(method).get(paramIndex);
   }
 
   private static boolean isSpecialParameter(Class<?> clazz) {

src/main/java/org/apache/ibatis/reflection/ParamNameUtil.java

@@ -22,9 +22,6 @@
 import java.util.ArrayList;
 import java.util.List;
 
-import org.apache.ibatis.lang.UsesJava8;
-
-@UsesJava8
 public class ParamNameUtil {
   public static List<String> getParamNames(Method method) {
     return getParameterNames(method);

src/main/java/org/apache/ibatis/type/InstantTypeHandler.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2017 the original author or authors.
+ *    Copyright 2009-2018 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -22,13 +22,10 @@
 import java.sql.Timestamp;
 import java.time.Instant;
 
-import org.apache.ibatis.lang.UsesJava8;
-
 /**
  * @since 3.4.5
  * @author Tomas Rohovsky
  */
-@UsesJava8
 public class InstantTypeHandler extends BaseTypeHandler<Instant> {
 
   @Override

src/main/java/org/apache/ibatis/type/JapaneseDateTypeHandler.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2017 the original author or authors.
+ *    Copyright 2009-2018 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -23,15 +23,12 @@
 import java.time.LocalDate;
 import java.time.chrono.JapaneseDate;
 
-import org.apache.ibatis.lang.UsesJava8;
-
 /**
  * Type Handler for {@link JapaneseDate}.
  *
  * @since 3.4.5
  * @author Kazuki Shimizu
  */
-@UsesJava8
 public class JapaneseDateTypeHandler extends BaseTypeHandler<JapaneseDate> {
 
   @Override