diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/JUnitMethodDeclarationCheck.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/JUnitMethodDeclarationCheck.java
index b85bae0314..a3ba086c53 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/JUnitMethodDeclarationCheck.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/JUnitMethodDeclarationCheck.java
@@ -40,7 +40,7 @@
 /** A {@link BugChecker} which flags non-canonical JUnit method declarations. */
 // XXX: Consider introducing a class-level check which enforces that test classes:
 // 1. Are named `*Test` or `Abstract*TestCase`.
-// 2. If not `abstract`, don't have public methods and subclasses.
+// 2. If not `abstract`, are package-private and don't have public methods and subclasses.
 // 3. Only have private fields.
 // XXX: If implemented, the current logic could flag only `private` JUnit methods.
 @AutoService(BugChecker.class)
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AnnotationAttributeMatcherTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AnnotationAttributeMatcherTest.java
index fbd2cef581..46b4c52bd6 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AnnotationAttributeMatcherTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AnnotationAttributeMatcherTest.java
@@ -6,7 +6,7 @@
 import java.util.Optional;
 import org.junit.jupiter.api.Test;
 
-public final class AnnotationAttributeMatcherTest {
+final class AnnotationAttributeMatcherTest {
   @Test
   void withoutListings() {
     AnnotationAttributeMatcher matcher =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AutowiredConstructorCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AutowiredConstructorCheckTest.java
index 7943abb8bd..78b1a56a53 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AutowiredConstructorCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AutowiredConstructorCheckTest.java
@@ -5,7 +5,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class AutowiredConstructorCheckTest {
+final class AutowiredConstructorCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(AutowiredConstructorCheck.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/CanonicalAnnotationSyntaxCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/CanonicalAnnotationSyntaxCheckTest.java
index 5a31aa5ad1..18bd06182d 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/CanonicalAnnotationSyntaxCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/CanonicalAnnotationSyntaxCheckTest.java
@@ -5,7 +5,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class CanonicalAnnotationSyntaxCheckTest {
+final class CanonicalAnnotationSyntaxCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(CanonicalAnnotationSyntaxCheck.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/EmptyMethodCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/EmptyMethodCheckTest.java
index 75956cd4a6..f206423db5 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/EmptyMethodCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/EmptyMethodCheckTest.java
@@ -5,7 +5,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class EmptyMethodCheckTest {
+final class EmptyMethodCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(EmptyMethodCheck.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/FormatStringConcatenationCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/FormatStringConcatenationCheckTest.java
index 7ca9d88070..68c6e0adea 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/FormatStringConcatenationCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/FormatStringConcatenationCheckTest.java
@@ -5,7 +5,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class FormatStringConcatenationCheckTest {
+final class FormatStringConcatenationCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(FormatStringConcatenationCheck.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationAttributeListingCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationAttributeListingCheckTest.java
index fdc54c811a..4b3bc78381 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationAttributeListingCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationAttributeListingCheckTest.java
@@ -6,7 +6,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class LexicographicalAnnotationAttributeListingCheckTest {
+final class LexicographicalAnnotationAttributeListingCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(
           LexicographicalAnnotationAttributeListingCheck.class, getClass());
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationListingCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationListingCheckTest.java
index 0b03ee6f07..e251863eb5 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationListingCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationListingCheckTest.java
@@ -7,7 +7,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class LexicographicalAnnotationListingCheckTest {
+final class LexicographicalAnnotationListingCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(LexicographicalAnnotationListingCheck.class, getClass())
           .expectErrorMessage(
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MethodMatcherFactoryTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MethodMatcherFactoryTest.java
index 5ef8f3347d..2c16a5db21 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MethodMatcherFactoryTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MethodMatcherFactoryTest.java
@@ -15,7 +15,7 @@
 import com.sun.source.tree.MethodInvocationTree;
 import org.junit.jupiter.api.Test;
 
-public final class MethodMatcherFactoryTest {
+final class MethodMatcherFactoryTest {
   /** A {@link BugChecker} which flags method invocations matched by {@link #TEST_MATCHER}. */
   @BugPattern(
       name = "MatchedMethodsFlagger",
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MethodReferenceUsageCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MethodReferenceUsageCheckTest.java
index 0fd50ad7aa..ede6dbe706 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MethodReferenceUsageCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MethodReferenceUsageCheckTest.java
@@ -5,7 +5,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class MethodReferenceUsageCheckTest {
+final class MethodReferenceUsageCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(MethodReferenceUsageCheck.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MissingRefasterAnnotationCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MissingRefasterAnnotationCheckTest.java
index 5ef92360f1..ed429e9ecf 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MissingRefasterAnnotationCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MissingRefasterAnnotationCheckTest.java
@@ -5,7 +5,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class MissingRefasterAnnotationCheckTest {
+final class MissingRefasterAnnotationCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(MissingRefasterAnnotationCheck.class, getClass())
           .expectErrorMessage(
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MockitoStubbingCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MockitoStubbingCheckTest.java
index 81a5d8854e..0525d30c7d 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MockitoStubbingCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MockitoStubbingCheckTest.java
@@ -5,7 +5,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class MockitoStubbingCheckTest {
+final class MockitoStubbingCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(MockitoStubbingCheck.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/PrimitiveComparisonCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/PrimitiveComparisonCheckTest.java
index 90e9cf9727..d49772a741 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/PrimitiveComparisonCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/PrimitiveComparisonCheckTest.java
@@ -5,7 +5,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class PrimitiveComparisonCheckTest {
+final class PrimitiveComparisonCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(PrimitiveComparisonCheck.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RedundantStringConversionCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RedundantStringConversionCheckTest.java
index 386f614004..3f4bf00db3 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RedundantStringConversionCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RedundantStringConversionCheckTest.java
@@ -9,7 +9,7 @@
 // XXX: The tests below show that `String.valueOf((String) null)` may be simplified, but
 // `String.valueOf(null)` may not. That is because the latter matches `String#valueOf(char[])`. We
 // could special-case `null` arguments, but that doesn't seem worth the trouble.
-public final class RedundantStringConversionCheckTest {
+final class RedundantStringConversionCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(RedundantStringConversionCheck.class, getClass());
   private final CompilationTestHelper customizedCompilationTestHelper =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RefasterAnyOfUsageCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RefasterAnyOfUsageCheckTest.java
index 1ac693e444..f48d3afb20 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RefasterAnyOfUsageCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RefasterAnyOfUsageCheckTest.java
@@ -5,7 +5,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class RefasterAnyOfUsageCheckTest {
+final class RefasterAnyOfUsageCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(RefasterAnyOfUsageCheck.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RefasterCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RefasterCheckTest.java
index e88218f011..9f4686e4cc 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RefasterCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RefasterCheckTest.java
@@ -19,7 +19,7 @@
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
 
-public final class RefasterCheckTest {
+final class RefasterCheckTest {
   /** The names of all Refaster template groups defined in this module. */
   private static final ImmutableSet<String> TEMPLATE_GROUPS =
       ImmutableSet.of(
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ScheduledTransactionTraceCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ScheduledTransactionTraceCheckTest.java
index e56f831d80..7446fad733 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ScheduledTransactionTraceCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ScheduledTransactionTraceCheckTest.java
@@ -7,7 +7,7 @@
 import org.junit.jupiter.api.condition.DisabledForJreRange;
 import org.junit.jupiter.api.condition.JRE;
 
-public final class ScheduledTransactionTraceCheckTest {
+final class ScheduledTransactionTraceCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(ScheduledTransactionTraceCheck.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/Slf4jLogStatementCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/Slf4jLogStatementCheckTest.java
index 762244f472..3a56d70ee9 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/Slf4jLogStatementCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/Slf4jLogStatementCheckTest.java
@@ -5,7 +5,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class Slf4jLogStatementCheckTest {
+final class Slf4jLogStatementCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(Slf4jLogStatementCheck.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/SpringMvcAnnotationCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/SpringMvcAnnotationCheckTest.java
index 76fae4bf8e..842e08e556 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/SpringMvcAnnotationCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/SpringMvcAnnotationCheckTest.java
@@ -5,7 +5,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class SpringMvcAnnotationCheckTest {
+final class SpringMvcAnnotationCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(SpringMvcAnnotationCheck.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/StaticImportCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/StaticImportCheckTest.java
index 6379d5e3c9..398242a2a1 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/StaticImportCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/StaticImportCheckTest.java
@@ -7,7 +7,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class StaticImportCheckTest {
+final class StaticImportCheckTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(StaticImportCheck.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/TimeZoneUsageCheckTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/TimeZoneUsageCheckTest.java
index 170dfc1fc3..64f08ccbcf 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/TimeZoneUsageCheckTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/TimeZoneUsageCheckTest.java
@@ -5,7 +5,7 @@
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class TimeZoneUsageCheckTest {
+final class TimeZoneUsageCheckTest {
   private final CompilationTestHelper compilationHelper =
       CompilationTestHelper.newInstance(TimeZoneUsageCheck.class, getClass())
           .expectErrorMessage(