Use normalized line separators with IntelliJ

Update `SpringReformatter` used with IntelliJ to explicitly use
the normalized `\n` line separator rather than relying on the
system line.separator value.

Closes gh-65

Author: philwebb

spring-javaformat-intellij/spring-javaformat-intellij-plugin/src/main/java/io/spring/format/formatter/intellij/codestyle/SpringReformatter.java

@@ -45,6 +45,8 @@
  */
 class SpringReformatter {
 
+	private static final String NORMALIZED_LINE_SEPARATOR = "\n";
+
 	private final Supplier<Project> project;
 
 	private final Supplier<Application> application;
@@ -101,7 +103,7 @@ private void reformat(PsiFile file, Collection<TextRange> ranges, Document docum
 			Formatter formatter = new Formatter();
 			String source = document.getText();
 			IRegion[] regions = EclipseRegionAdapter.asArray(ranges);
-			TextEdit edit = formatter.format(source, regions);
+			TextEdit edit = formatter.format(source, regions, NORMALIZED_LINE_SEPARATOR);
 			applyEdit(document, edit);
 		}
 	}

spring-javaformat/spring-javaformat-formatter/src/main/java/io/spring/javaformat/formatter/Formatter.java

@@ -112,8 +112,19 @@ public TextEdit format(int kind, String source, int offset, int length,
 	 * @return the text edit
 	 */
 	public TextEdit format(String source, IRegion[] regions) {
+		return format(source, regions, DEFAULT_LINE_SEPARATOR);
+	}
+
+	/**
+	 * Format specific subsections of the given source content.
+	 * @param source the source content to format
+	 * @param regions the regions to format
+	 * @param lineSeparator the line separator
+	 * @return the text edit
+	 */
+	public TextEdit format(String source, IRegion[] regions, String lineSeparator) {
 		return format(DEFAULT_COMPONENTS, source, regions, DEFAULT_INDENTATION_LEVEL,
-				DEFAULT_LINE_SEPARATOR);
+				lineSeparator);
 	}
 
 	@Override