Require JDK 17 rather than JDK 11 (#603)

By raising this baseline the project can now use Java 17 language features such
as text blocks, switch expressions and `instanceof` pattern matching. The code
has been updated to make use of these constructs.

Note that the project can still be used by builds that target an older version
of Java, as long as those builds are executed using JDK 17+.

error-prone-guidelines/src/main/java/tech/picnic/errorprone/guidelines/bugpatterns/ErrorProneRuntimeClasspath.java

@@ -50,8 +50,9 @@ import tech.picnic.errorprone.utils.ThirdPartyLibrary;
 @AutoService(BugChecker.class)
 @BugPattern(
     summary =
-        "Prefer `Class#getCanonicalName()` over an equivalent string literal if and only if the "
-            + "type will be on the runtime classpath",
+        """
+        Prefer `Class#getCanonicalName()` over an equivalent string literal if and only if the \
+        type will be on the runtime classpath""",
     link = BUG_PATTERNS_BASE_URL + "ErrorProneRuntimeClasspath",
     linkType = CUSTOM,
     severity = SUGGESTION,

error-prone-guidelines/src/main/java/tech/picnic/errorprone/guidelines/bugpatterns/ExhaustiveRefasterTypeMigration.java

@@ -72,8 +72,9 @@ import org.jspecify.annotations.Nullable;
 @AutoService(BugChecker.class)
 @BugPattern(
     summary =
-        "The set of unmigrated methods listed by the `@TypeMigration` annotation must be minimal "
-            + "yet exhaustive",
+        """
+        The set of unmigrated methods listed by the `@TypeMigration` annotation must be minimal \
+        yet exhaustive""",
     link = BUG_PATTERNS_BASE_URL + "ExhaustiveRefasterTypeMigration",
     linkType = CUSTOM,
     severity = WARNING,

error-prone-guidelines/src/main/java/tech/picnic/errorprone/guidelines/bugpatterns/RefasterAnyOfUsage.java

@@ -42,21 +42,18 @@ public final class RefasterAnyOfUsage extends BugChecker implements MethodInvoca
 
   @Override
   public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
-    if (REFASTER_ANY_OF.matches(tree, state)) {
-      switch (tree.getArguments().size()) {
-        case 0:
-          // We can't safely fix this case; dropping the expression may produce non-compilable code.
-          return describeMatch(tree);
-        case 1:
-          return describeMatch(
-              tree,
-              SuggestedFix.replace(
-                  tree, SourceCode.treeToString(tree.getArguments().get(0), state)));
-        default:
-          /* Handled below. */
-      }
+    int argumentCount = tree.getArguments().size();
+    if (argumentCount > 1 || !REFASTER_ANY_OF.matches(tree, state)) {
+      return Description.NO_MATCH;
     }
 
-    return Description.NO_MATCH;
+    if (argumentCount == 0) {
+      /* We can't safely fix this case; dropping the expression may produce non-compilable code. */
+      return describeMatch(tree);
+    }
+
+    return describeMatch(
+        tree,
+        SuggestedFix.replace(tree, SourceCode.treeToString(tree.getArguments().get(0), state)));
   }
 }

error-prone-guidelines/src/main/java/tech/picnic/errorprone/guidelines/bugpatterns/UnqualifiedSuggestedFixImport.java

@@ -45,16 +45,14 @@ public final class UnqualifiedSuggestedFixImport extends BugChecker
       return Description.NO_MATCH;
     }
 
-    switch (ASTHelpers.getSymbol(tree).getSimpleName().toString()) {
-      case "addImport":
-        return createDescription(
-            tree, "SuggestedFix.Builder#addImport", "SuggestedFixes#qualifyType");
-      case "addStaticImport":
-        return createDescription(
-            tree, "SuggestedFix.Builder#addStaticImport", "SuggestedFixes#qualifyStaticImport");
-      default:
-        return Description.NO_MATCH;
-    }
+    return switch (ASTHelpers.getSymbol(tree).getSimpleName().toString()) {
+      case "addImport" ->
+          createDescription(tree, "SuggestedFix.Builder#addImport", "SuggestedFixes#qualifyType");
+      case "addStaticImport" ->
+          createDescription(
+              tree, "SuggestedFix.Builder#addStaticImport", "SuggestedFixes#qualifyStaticImport");
+      default -> Description.NO_MATCH;
+    };
   }
 
   private Description createDescription(