[test] remove Java source level 1.5 workaround

to avoid warnings in build output

#2975

org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/util/TestVerifier.java

@@ -20,12 +20,12 @@
 import java.io.*;
 import java.lang.ref.Cleaner;
 import java.net.*;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.function.Supplier;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
 
 /**
  * Verifies that the .class files resulting from a compilation can be loaded
@@ -377,7 +377,7 @@ public String getExecutionError(){
  * {@link #READ_VERIFY_TEST_FROM_FILE} after calling this method for the first time, the return value will not change
  * anymore.
  *
- * @return {@link VerifyTests} source code, filtered by {@link #filterSourceCode(Stream)}
+ * @return {@link VerifyTests} source code
  */
 String getVerifyTestsCode() {
 	synchronized (verifyTestCodeLock) {
@@ -387,8 +387,8 @@ String getVerifyTestsCode() {
 				if (!new File(sourceFile).exists()) {
 					sourceFile = PROJECT_BASE_DIR + "/org.eclipse.jdt.core.tests.compiler/" + sourceFile;
 				}
-				try (BufferedReader reader = new BufferedReader(new FileReader(sourceFile))) {
-					verifyTestCode = filterSourceCode(reader.lines());
+				try {
+					verifyTestCode=Files.readString(Path.of(sourceFile));
 				}
 				catch (IOException e) {
 					System.out.println("WARNING: Cannot read & filter VerifyTests source code from file, using default value");
@@ -397,35 +397,12 @@ String getVerifyTestsCode() {
 			}
 		}
 		if (verifyTestCode == null) {
-			try (BufferedReader reader = new BufferedReader(new StringReader(VERIFY_TEST_CODE_DEFAULT))) {
-				verifyTestCode = filterSourceCode(reader.lines());
-			}
-			catch (IOException e) {
-				System.out.println("WARNING: Cannot filter VerifyTests source code default value, using unfiltered value");
-				System.out.println("	- exception: " + e);
-				verifyTestCode = VERIFY_TEST_CODE_DEFAULT;
-			}
+			verifyTestCode = VERIFY_TEST_CODE_DEFAULT;
 		}
 		return verifyTestCode;
 	}
 }
 
-/**
- * Filter some elements incompatible with Java source level 1.5 from source code
- * <p>
- * This method cannot convert things like catch-with-resources or other language elements back to Java 1.5, you have to
- * take care of keeping the source code backward compatible by yourself. But a few things you can still use in the
- * source code, such as {@code @SuppressWarnings}, {@code @Override} in interfaces or single-line {@code assert}.
- *
- * @param sourceCodeLines stream of source code lines
- * @return filtered source code file as a string
- */
-private String filterSourceCode(Stream<String> sourceCodeLines) {
-	return sourceCodeLines
-		.filter(s -> !(s.contains("@SuppressWarnings") || s.contains("@Override") || s.contains("assert ")))
-		.collect(Collectors.joining("\n"));
-}
-
 /**
  * Remove non-essential parts of the test JVM classpath
  * <p>