Replace concatenates Strings by Text-Blocks in CompilerTests

This improves the readability of Strings defining the test-input and
expected output. It avoids the need to explicitly add new-line
characters and the need to escape double-quotes.

org.eclipse.xtext.xbase.tests/.classpath

@@ -20,7 +20,7 @@
 			<attribute name="test" value="true"/>
 		</attributes>
 	</classpathentry>
-	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-11/"/>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-17"/>
 	<classpathentry kind="con" path="org.eclipse.pde.core.requiredPlugins"/>
 	<classpathentry kind="output" path="target/classes"/>
 </classpath>

org.eclipse.xtext.xbase.tests/.settings/org.eclipse.jdt.core.prefs

@@ -24,9 +24,9 @@ org.eclipse.jdt.core.compiler.annotation.nonnullisdefault=disabled
 org.eclipse.jdt.core.compiler.annotation.nullable=org.eclipse.jdt.annotation.Nullable
 org.eclipse.jdt.core.compiler.annotation.nullanalysis=disabled
 org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
-org.eclipse.jdt.core.compiler.codegen.targetPlatform=11
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=17
 org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
-org.eclipse.jdt.core.compiler.compliance=11
+org.eclipse.jdt.core.compiler.compliance=17
 org.eclipse.jdt.core.compiler.debug.lineNumber=generate
 org.eclipse.jdt.core.compiler.debug.localVariable=generate
 org.eclipse.jdt.core.compiler.debug.sourceFile=generate
@@ -132,7 +132,7 @@ org.eclipse.jdt.core.compiler.problem.unusedPrivateMember=warning
 org.eclipse.jdt.core.compiler.problem.unusedWarningToken=warning
 org.eclipse.jdt.core.compiler.problem.varargsArgumentNeedCast=warning
 org.eclipse.jdt.core.compiler.release=enabled
-org.eclipse.jdt.core.compiler.source=11
+org.eclipse.jdt.core.compiler.source=17
 org.eclipse.jdt.core.formatter.align_type_members_on_columns=false
 org.eclipse.jdt.core.formatter.alignment_for_additive_operator=16
 org.eclipse.jdt.core.formatter.alignment_for_arguments_in_allocation_expression=16

org.eclipse.xtext.xbase.tests/META-INF/MANIFEST.MF

@@ -3,7 +3,7 @@ Bundle-ManifestVersion: 2
 Bundle-Name: Xbase Runtime Tests
 Bundle-SymbolicName: org.eclipse.xtext.xbase.tests;singleton:=true
 Bundle-Version: 2.35.0.qualifier
-Bundle-RequiredExecutionEnvironment: JavaSE-11
+Bundle-RequiredExecutionEnvironment: JavaSE-17
 Require-Bundle: org.eclipse.xtext.xbase;bundle-version="2.35.0",
  org.eclipse.xtext;bundle-version="2.35.0",
  org.eclipse.xtext.testing;bundle-version="2.35.0",