fixed findPlaceholderEndIndex to work with a custom suffix as well (SPR-7574)

git-svn-id: https://src.springframework.org/svn/spring-framework/trunk@3697 50f2f4bb-b051-0410-bef5-90022cba6387

org.springframework.core/src/main/java/org/springframework/util/PropertyPlaceholderHelper.java

@@ -190,7 +190,7 @@ public class PropertyPlaceholderHelper {
 			if (StringUtils.substringMatch(buf, index, this.placeholderSuffix)) {
 				if (withinNestedPlaceholder > 0) {
 					withinNestedPlaceholder--;
-					index = index + this.placeholderPrefix.length() - 1;
+					index = index + this.placeholderSuffix.length();
 				}
 				else {
 					return index;