Update OriginTrackedPropertiesLoader to ISO 8859-1

Align `OriginTrackedPropertiesLoader` with Java default property loading
by using ISO 8859-1 character encoding.

Closes gh-10565

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/env/OriginTrackedPropertiesLoader.java

@@ -37,6 +37,7 @@ import org.springframework.util.Assert;
  *
  * @author Madhura Bhave
  * @author Phillip Webb
+ * @author Thiago Hirata
  */
 class OriginTrackedPropertiesLoader {
 
@@ -154,7 +155,7 @@ class OriginTrackedPropertiesLoader {
 
 		CharacterReader(Resource resource) throws IOException {
 			this.reader = new LineNumberReader(
-					new InputStreamReader(resource.getInputStream()));
+					new InputStreamReader(resource.getInputStream(), "8859_1"));
 		}
 
 		@Override

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/env/OriginTrackedPropertiesLoaderTests.java

@@ -228,6 +228,12 @@ public class OriginTrackedPropertiesLoaderTests {
 		assertThat(getLocation(mango)).isEqualTo("27:1");
 	}
 
+	@Test
+	public void getPropertyWithISO88591Character() throws Exception {
+		OriginTrackedValue value = this.properties.get("test-iso8859-1-chars");
+		assertThat(getValue(value)).isEqualTo("æ×ÈÅÞßáñÀÿ");
+	}
+
 	private Object getValue(OriginTrackedValue value) {
 		return (value == null ? null : value.getValue());
 	}

spring-boot-project/spring-boot/src/test/resources/org/springframework/boot/env/test-properties.properties

@@ -37,3 +37,6 @@ test-property-value-comment=foo \
 !bar #foo
 test-multiline-immediate-bang=\
 !foo
+
+#test ISO 8859-1
+test-iso8859-1-chars=
\ No newline at end of file