diff --git a/.github/workflows/build-jdk11.yaml b/.github/workflows/build-jdk11.yaml
index 780668694c5..9ed337f2609 100644
--- a/.github/workflows/build-jdk11.yaml
+++ b/.github/workflows/build-jdk11.yaml
@@ -14,11 +14,11 @@ jobs:
       # the code is compiled using JDK 17, while the tests are executed
       # using JDK 11.
       - name: Check out code
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
+        uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # v3.6.0
         with:
           persist-credentials: false
       - name: Set up JDK
-        uses: actions/setup-java@5ffc13f4174014e2d4d4572b3d74c3fa61aeb2c2 # v3.11.0
+        uses: actions/setup-java@cd89f46ac9d01407894225f350157564c9c7cee2 # v3.12.0
         with:
           java-version: |
             11.0.19
diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/ImmutablesSortedSetComparator.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/ImmutablesSortedSetComparator.java
index 468a2dcc826..0d7446a2066 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/ImmutablesSortedSetComparator.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/ImmutablesSortedSetComparator.java
@@ -43,8 +43,9 @@
 @AutoService(BugChecker.class)
 @BugPattern(
     summary =
-        "`SortedSet` properties of a `@Value.Immutable` or `@Value.Modifiable` type must be "
-            + "annotated with `@Value.NaturalOrder` or `@Value.ReverseOrder`",
+        """
+        `SortedSet` properties of a `@Value.Immutable` or `@Value.Modifiable` type must be \
+        annotated with `@Value.NaturalOrder` or `@Value.ReverseOrder`""",
     link = BUG_PATTERNS_BASE_URL + "ImmutablesSortedSetComparator",
     linkType = CUSTOM,
     severity = ERROR,
diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NestedPublishers.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NestedPublishers.java
index d4f00b99b13..da0761b4eec 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NestedPublishers.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NestedPublishers.java
@@ -34,8 +34,9 @@
 @AutoService(BugChecker.class)
 @BugPattern(
     summary =
-        "Avoid `Publisher`s that emit other `Publishers`s; "
-            + "the resultant code is hard to reason about",
+        """
+        Avoid `Publisher`s that emit other `Publishers`s; the resultant code is hard to reason \
+        about""",
     link = BUG_PATTERNS_BASE_URL + "NestedPublishers",
     linkType = CUSTOM,
     severity = WARNING,
diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/PrimitiveComparison.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/PrimitiveComparison.java
index 997a52f644e..28c7b02c776 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/PrimitiveComparison.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/PrimitiveComparison.java
@@ -44,8 +44,9 @@
 @AutoService(BugChecker.class)
 @BugPattern(
     summary =
-        "Ensure invocations of `Comparator#comparing{,Double,Int,Long}` match the return type"
-            + " of the provided function",
+        """
+        Ensure invocations of `Comparator#comparing{,Double,Int,Long}` match the return type of \
+        the provided function""",
     link = BUG_PATTERNS_BASE_URL + "PrimitiveComparison",
     linkType = CUSTOM,
     severity = WARNING,
diff --git a/pom.xml b/pom.xml
index ea2fb187d2d..ff380c5f1fb 100644
--- a/pom.xml
+++ b/pom.xml
@@ -1892,9 +1892,9 @@
             <properties>
                 <maven.test.failure.ignore>true</maven.test.failure.ignore>
                 <!-- Normal builds use Jabel to target an older JDK version
-                than what would normally be supported given the language
-                features used, but this causes Sonar to report parse errors.
-                So for Sonar builds we target a JDK version that is properly
+                than any that would normally be supported given the language
+                features used, but this causes Sonar to report parse errors. So
+                for Sonar builds we target a JDK version that is properly
                 compatible with the source code. -->
                 <version.jdk.target>${version.jdk.source}</version.jdk.target>
             </properties>
diff --git a/refaster-support/src/main/java/tech/picnic/errorprone/refaster/matchers/IsLikelyTrivialComputation.java b/refaster-support/src/main/java/tech/picnic/errorprone/refaster/matchers/IsLikelyTrivialComputation.java
index 9cfa30b5110..dbf56e80e6b 100644
--- a/refaster-support/src/main/java/tech/picnic/errorprone/refaster/matchers/IsLikelyTrivialComputation.java
+++ b/refaster-support/src/main/java/tech/picnic/errorprone/refaster/matchers/IsLikelyTrivialComputation.java
@@ -23,7 +23,7 @@ public IsLikelyTrivialComputation() {}
 
   @Override
   public boolean matches(ExpressionTree expressionTree, VisitorState state) {
-    if (expressionTree instanceof MethodInvocationTree) {
+    if (expressionTree instanceof MethodInvocationTree methodInvocation) {
       // XXX: Method invocations are generally *not* trivial computations, but we make an exception
       // for nullary method invocations on the result of a trivial computation. This exception
       // allows this `Matcher` to by the `OptionalOrElseGet` Refaster rule, such that it does not
@@ -31,7 +31,6 @@ public boolean matches(ExpressionTree expressionTree, VisitorState state) {
       // references. Once the `MethodReferenceUsage` bug checker is production-ready, this exception
       // should be removed. (But at that point, instead defining a `RequiresComputation` matcher may
       // be more appropriate.)
-      MethodInvocationTree methodInvocation = (MethodInvocationTree) expressionTree;
       if (methodInvocation.getArguments().isEmpty()
           && matches(methodInvocation.getMethodSelect())) {
         return true;
@@ -44,9 +43,8 @@ && matches(methodInvocation.getMethodSelect())) {
   // XXX: Some `BinaryTree`s may represent what could be considered "trivial computations".
   // Depending on feedback such trees may be matched in the future.
   private static boolean matches(ExpressionTree expressionTree) {
-    if (expressionTree instanceof ArrayAccessTree) {
-      return matches(((ArrayAccessTree) expressionTree).getExpression())
-          && matches(((ArrayAccessTree) expressionTree).getIndex());
+    if (expressionTree instanceof ArrayAccessTree arrayAccess) {
+      return matches(arrayAccess.getExpression()) && matches(arrayAccess.getIndex());
     }
 
     if (expressionTree instanceof LiteralTree) {
@@ -65,26 +63,26 @@ private static boolean matches(ExpressionTree expressionTree) {
       return true;
     }
 
-    if (expressionTree instanceof MemberReferenceTree) {
-      return matches(((MemberReferenceTree) expressionTree).getQualifierExpression());
+    if (expressionTree instanceof MemberReferenceTree memberReference) {
+      return matches(memberReference.getQualifierExpression());
     }
 
-    if (expressionTree instanceof MemberSelectTree) {
-      return matches(((MemberSelectTree) expressionTree).getExpression());
+    if (expressionTree instanceof MemberSelectTree memberSelect) {
+      return matches(memberSelect.getExpression());
     }
 
-    if (expressionTree instanceof ParenthesizedTree) {
-      return matches(((ParenthesizedTree) expressionTree).getExpression());
+    if (expressionTree instanceof ParenthesizedTree parenthesized) {
+      return matches(parenthesized.getExpression());
     }
 
-    if (expressionTree instanceof TypeCastTree) {
-      return matches(((TypeCastTree) expressionTree).getExpression());
+    if (expressionTree instanceof TypeCastTree typeCast) {
+      return matches(typeCast.getExpression());
     }
 
-    if (expressionTree instanceof UnaryTree) {
+    if (expressionTree instanceof UnaryTree unary) {
       // XXX: Arguably side-effectful options such as pre- and post-increment and -decrement are not
       // trivial.
-      return matches(((UnaryTree) expressionTree).getExpression());
+      return matches(unary.getExpression());
     }
 
     return false;
diff --git a/refaster-support/src/main/java/tech/picnic/errorprone/refaster/matchers/ThrowsCheckedException.java b/refaster-support/src/main/java/tech/picnic/errorprone/refaster/matchers/ThrowsCheckedException.java
index aa11abcdf34..ed758cbcddc 100644
--- a/refaster-support/src/main/java/tech/picnic/errorprone/refaster/matchers/ThrowsCheckedException.java
+++ b/refaster-support/src/main/java/tech/picnic/errorprone/refaster/matchers/ThrowsCheckedException.java
@@ -7,7 +7,6 @@
 import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.LambdaExpressionTree;
 import com.sun.source.tree.MemberReferenceTree;
-import com.sun.tools.javac.code.Symbol;
 import com.sun.tools.javac.code.Type;
 import com.sun.tools.javac.code.Types.FunctionDescriptorLookupError;
 import java.util.Collection;
@@ -33,13 +32,8 @@ private static Collection<Type> getThrownTypes(ExpressionTree tree, VisitorState
       return ASTHelpers.getThrownExceptions(lambdaExpression.getBody(), state);
     }
 
-    if (tree instanceof MemberReferenceTree) {
-      Symbol symbol = ASTHelpers.getSymbol(tree);
-      if (symbol == null) {
-        return ImmutableSet.of();
-      }
-
-      return symbol.type.getThrownTypes();
+    if (tree instanceof MemberReferenceTree memberReference) {
+      return ASTHelpers.getSymbol(memberReference).type.getThrownTypes();
     }
 
     Type type = ASTHelpers.getType(tree);