Add @Nullable annotations to methods, parameters, and return types across multiple classes to improve null-safety.

Author: jbl428

buildSrc/src/main/kotlin/com/navercorp/fixturemonkey/gradle/plugin/CheckerFrameworkConventionsPlugin.kt

@@ -29,6 +29,10 @@ class CheckerFrameworkConventionsPlugin : Plugin<Project> {
 
         project.extensions.getByType<CheckerFrameworkExtension>().apply {
             checkers = listOf("org.checkerframework.checker.nullness.NullnessChecker")
+            extraJavacArgs = listOf(
+                "-AsuppressWarnings=initialization,method.invocation,type.arguments"
+            )
+            excludeTests = true
         }
     }
 }

fixture-monkey-api/build.gradle.kts

@@ -19,6 +19,9 @@ multiReleaseVersions.forEach { releaseVersion ->
                 .replaceFirstChar { it.lowercase() }
 
             configuration.extendsFrom(configurations.getByName(defaultVersionConfigurationName))
+
+            val checkerFrameworkExtension = project.extensions.findByType<org.checkerframework.gradle.plugin.CheckerFrameworkExtension>()
+            checkerFrameworkExtension?.skipCheckerFramework = true
         }
 }
 

fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/arbitrary/ContainerCombinableArbitrary.java

@@ -48,6 +48,7 @@ final class ContainerCombinableArbitrary<T> implements CombinableArbitrary<T> {
 	}
 
 	@Override
+	@SuppressWarnings("type.arguments.not.inferred")
 	public T combined() {
 		List<Object> combinedList = combinableArbitraryList.stream()
 			.map(CombinableArbitrary::combined)
@@ -57,6 +58,7 @@ public T combined() {
 	}
 
 	@Override
+	@SuppressWarnings({"return"})
 	public Object rawValue() {
 		List<Object> rawValues = combinableArbitraryList.stream()
 			.map(CombinableArbitrary::rawValue)
@@ -85,6 +87,7 @@ public boolean fixed() {
 	}
 
 	@Override
+	@SuppressWarnings("argument")
 	public CombinableArbitrary<T> unique() {
 		List<CombinableArbitrary<?>> uniqueCombinableArbitraryList = this.combinableArbitraryList.stream()
 			.map(arbitrary -> arbitrary.filter(it -> {

fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/arbitrary/FilteredCombinableArbitrary.java

@@ -123,7 +123,7 @@ public T combined() {
 		throw newRetryableFilterMissException(lastException);
 	}
 
-	@SuppressWarnings("unchecked")
+	@SuppressWarnings({"unchecked", "override.return", "argument"})
 	@Override
 	public T rawValue() {
 		T returned;
@@ -205,6 +205,7 @@ public CombinableArbitrary<T> unique() {
 		return combinableArbitrary.unique();
 	}
 
+	@SuppressWarnings("argument")
 	private RetryableFilterMissException newRetryableFilterMissException(@Nullable Throwable throwable) {
 		if (!(throwable instanceof RetryableFilterMissException)) {
 			return new RetryableFilterMissException(throwable);

fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/arbitrary/FixedCombinableArbitrary.java

@@ -22,6 +22,7 @@
 
 import org.apiguardian.api.API;
 import org.apiguardian.api.API.Status;
+import org.jspecify.annotations.Nullable;
 
 /**
  * It would generate a fixed value {@code object}.
@@ -40,6 +41,7 @@ public T combined() {
 	}
 
 	@Override
+	@SuppressWarnings("override.return")
 	public T rawValue() {
 		return object;
 	}
@@ -54,7 +56,7 @@ public boolean fixed() {
 	}
 
 	@Override
-	public boolean equals(Object obj) {
+	public boolean equals(@Nullable Object obj) {
 		if (this == obj) {
 			return true;
 		}

fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/arbitrary/LazyCombinableArbitrary.java

@@ -43,6 +43,7 @@ public T combined() {
 	}
 
 	@Override
+	@SuppressWarnings("return")
 	public Object rawValue() {
 		Object rawValue = introspected.getValue();
 		introspected.clear();

fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/arbitrary/MappedCombinableArbitrary.java

@@ -43,9 +43,9 @@ public U combined() {
 		return mapper.apply(combinableArbitrary.combined());
 	}
 
-	@SuppressWarnings("unchecked")
+	@SuppressWarnings({"unchecked", "return"})
 	@Override
-	public U rawValue() {
+	public Object rawValue() {
 		try {
 			return mapper.apply((T)combinableArbitrary.rawValue());
 		} catch (ClassCastException ex) {

fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/arbitrary/MonkeyStringArbitrary.java

@@ -32,6 +32,8 @@
 
 import org.apiguardian.api.API;
 import org.apiguardian.api.API.Status;
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
 
 import net.jqwik.api.Arbitrary;
 import net.jqwik.api.EdgeCases;
@@ -57,16 +59,17 @@ public final class MonkeyStringArbitrary implements StringArbitrary {
 	private CharacterArbitrary characterArbitrary = new DefaultCharacterArbitrary();
 
 	private int minLength = 0;
-	private Integer maxLength = null;
+	private @Nullable Integer maxLength = null;
 	private Predicate<Character> filter = c -> true;
+	@SuppressWarnings("assignment")
 	private RandomDistribution lengthDistribution = null;
 	private double repeatChars = 0.0;
 
 	@Override
 	public RandomGenerator<String> generator(int genSize) {
 		long maxUniqueChars = characterArbitrary
 			.exhaustive(maxLength())
-			.map(ExhaustiveGenerator::maxCount)
+			.<@NonNull Long>map(ExhaustiveGenerator::maxCount)
 			.orElse((long)maxLength());
 		return RandomGenerators.strings(
 			randomCharacterGenerator(),
@@ -82,6 +85,7 @@ public RandomGenerator<String> generator(int genSize, boolean withEdgeCases) {
 		return this.generator(genSize);
 	}
 
+	@SuppressWarnings("argument")
 	private int maxLength() {
 		return RandomGenerators.collectionMaxSize(minLength, maxLength);
 	}
@@ -250,7 +254,7 @@ public StringArbitrary excludeChars(char... charsToExclude) {
 	}
 
 	@Override
-	public boolean equals(Object obj) {
+	public boolean equals(@Nullable Object obj) {
 		if (this == obj) {
 			return true;
 		}

fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/arbitrary/NullInjectCombinableArbitrary.java

@@ -39,7 +39,7 @@ final class NullInjectCombinableArbitrary<T> implements CombinableArbitrary<T> {
 		this.nullProbability = nullProbability;
 	}
 
-	@SuppressWarnings("unchecked")
+	@SuppressWarnings({"unchecked", "argument"})
 	@Override
 	public T combined() {
 		T combined = combinableArbitrary.combined();
@@ -50,6 +50,7 @@ public T combined() {
 		return (T)injectNull(combined);
 	}
 
+	@SuppressWarnings("return")
 	@Override
 	public Object rawValue() {
 		Object rawValue = combinableArbitrary.rawValue();

fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/arbitrary/ObjectCombinableArbitrary.java

@@ -43,6 +43,7 @@ final class ObjectCombinableArbitrary<T> implements CombinableArbitrary<T> {
 		this.combinator = combinator;
 	}
 
+	@SuppressWarnings("argument")
 	@Override
 	public T combined() {
 		Map<ArbitraryProperty, Object> combinedPropertyValuesByArbitraryProperty = new HashMap<>();
@@ -54,6 +55,7 @@ public T combined() {
 		return combinator.apply(combinedPropertyValuesByArbitraryProperty);
 	}
 
+	@SuppressWarnings({"return", "argument"})
 	@Override
 	public Object rawValue() {
 		Map<ArbitraryProperty, Object> rawPropertyValuesByArbitraryProperty = new HashMap<>();