Add -Dfile.encoding=UTF-8 into gradle.properties

To avoid wrong encoding during reading and writing files by the
`updateCopyrights` Gradle task, it is better to have an explicit
`-Dfile.encoding=UTF-8` before starting JVM.

* Fix `AbstractFilePayloadTransformerTests` for non-standard symbols in
the test data
* fix broken test
`FileToStringTransformerTests.transform_withWrongEncoding_notMatching()`

Author: artembilan

build.gradle

@@ -238,7 +238,7 @@ subprojects { subproject ->
 								def years = "$beginningYear-$now"
 								def sourceCode = file.text
 								sourceCode = sourceCode.replaceFirst(/20\d\d(-20\d\d)?/, years)
-								file.write(sourceCode)
+								file.text = sourceCode
 								println "Copyright updated for file: $file"
 							}
 							break

gradle.properties

@@ -1,2 +1,2 @@
 version=5.2.0.BUILD-SNAPSHOT
-org.gradle.jvmargs=-Xmx1536m
+org.gradle.jvmargs=-Xmx1536m -Dfile.encoding=UTF-8

spring-integration-file/src/test/java/org/springframework/integration/file/transformer/AbstractFilePayloadTransformerTests.java

@@ -38,7 +38,7 @@ public abstract class AbstractFilePayloadTransformerTests<T extends AbstractFile
 
 	static final String DEFAULT_ENCODING = "UTF-8";
 
-	static final String SAMPLE_CONTENT = "HelloWorld\n????";
+	static final String SAMPLE_CONTENT = "HelloWorld\näöüß";
 
 	T transformer;
 
@@ -48,7 +48,7 @@ public abstract class AbstractFilePayloadTransformerTests<T extends AbstractFile
 
 
 	@Before
-	public void setUpCommonTestdata() throws Exception {
+	public void setUpCommonTestData() throws Exception {
 		sourceFile = File.createTempFile("anyFile", ".txt");
 		sourceFile.deleteOnExit();
 		FileCopyUtils.copy(SAMPLE_CONTENT.getBytes(DEFAULT_ENCODING),
@@ -57,7 +57,7 @@ public void setUpCommonTestdata() throws Exception {
 	}
 
 	@After
-	public void tearDownCommonTestdata() {
+	public void tearDownCommonTestData() {
 		if (sourceFile.exists()) {
 			sourceFile.delete();
 		}

spring-integration-file/src/test/java/org/springframework/integration/file/transformer/FileToStringTransformerTests.java

@@ -52,7 +52,7 @@ public void transform_withWrongEncoding_notMatching() {
 		assertThat(result).isNotNull();
 		assertThat(result.getPayload())
 				.isInstanceOf(String.class)
-				.isEqualTo(SAMPLE_CONTENT);
+				.isNotEqualTo(SAMPLE_CONTENT);
 	}
 
 }