Add a missing test for "Fix properties parsing for comment chars"

Closes gh-8699

Author: izeye

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

@@ -111,6 +111,13 @@ public void getPropertyWithValueComment() throws Exception {
 		assertThat(getLocation(value)).isEqualTo("36:29");
 	}
 
+	@Test
+	public void getPropertyWithMultilineImmediateBang() {
+		OriginTrackedValue value = this.properties.get("test-multiline-immediate-bang");
+		assertThat(getValue(value)).isEqualTo("!foo");
+		assertThat(getLocation(value)).isEqualTo("39:1");
+	}
+
 	@Test
 	public void getPropertyWithCarriageReturn() throws Exception {
 		OriginTrackedValue value = this.properties.get("test-return-property");