fix code

hutool-core/src/main/java/cn/hutool/core/convert/impl/PrimitiveConverter.java

@@ -27,6 +27,9 @@ import java.util.function.Function;
 public class PrimitiveConverter extends AbstractConverter {
 	private static final long serialVersionUID = 1L;
 
+	/**
+	 * 单例对象
+	 */
 	public static final PrimitiveConverter INSTANCE = new PrimitiveConverter();
 
 	/**

hutool-core/src/test/java/cn/hutool/core/convert/PrimitiveConvertTest.java

@@ -1,5 +1,6 @@
 package cn.hutool.core.convert;
 
+import cn.hutool.core.convert.impl.PrimitiveConverter;
 import org.junit.Assert;
 import org.junit.Test;
 
@@ -15,4 +16,10 @@ public class PrimitiveConvertTest {
 	public void toIntErrorTest(){
 		final int convert = Convert.convert(int.class, "aaaa");
 	}
+
+	@Test
+	public void toIntValueTest() {
+		final Object a = PrimitiveConverter.INSTANCE.convert(int.class, null);
+		Assert.assertNull(a);
+	}
 }

hutool-core/src/test/java/cn/hutool/core/map/MapUtilTest.java

@@ -224,6 +224,16 @@ public class MapUtilTest {
 		Assert.assertNotNull(a);
 	}
 
+	@Test
+	public void getIntValueTest(){
+		final Map<String, String> map = MapUtil.ofEntries(MapUtil.entry("a", "1"), MapUtil.entry("b", null));
+		final int a = MapUtil.get(map, "a", int.class);
+		Assert.assertEquals(1, a);
+
+		final int b = MapUtil.getInt(map, "b", 0);
+		Assert.assertEquals(0, b);
+	}
+
 	@Test
 	public void valuesOfKeysTest() {
 		final Dict v1 = Dict.of().set("id", 12).set("name", "张三").set("age", 23);