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mark JsonTypeCoercer.coerce as nullable #17802

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3c3d56f
mark `JsonTypeCoercer.coerce` as nullable
asolntsev Jul 7, 2026
50d4a85
fix warnings
asolntsev Aug 4, 2026
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9 changes: 5 additions & 4 deletions java/src/org/openqa/selenium/json/CollectionCoercer.java
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Expand Up @@ -24,20 +24,21 @@
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Supplier;
import org.jspecify.annotations.Nullable;
import org.openqa.selenium.internal.Require;

class CollectionCoercer<T extends Collection, I extends T> extends TypeCoercer<T> {
class CollectionCoercer<T extends Collection<?>, I extends T> extends TypeCoercer<T> {

private final Class<T> stereotype;
private final JsonTypeCoercer coercer;
private final Supplier<I> supplier;
private final Function<I, Consumer<Object>> consumerFactory;
private final Function<I, Consumer<@Nullable Object>> consumerFactory;

public CollectionCoercer(
Class<T> stereotype,
JsonTypeCoercer coercer,
Supplier<I> supplier,
Function<I, Consumer<Object>> consumerFactory) {
Function<I, Consumer<@Nullable Object>> consumerFactory) {
this.stereotype = Require.nonNull("Stereotype", stereotype);
this.coercer = Require.nonNull("Coercer", coercer);
this.supplier = Require.nonNull("Supplier", supplier);
Expand Down Expand Up @@ -65,7 +66,7 @@ public BiFunction<JsonInput, PropertySetting, T> apply(Type type) {
return (jsonInput, setting) -> {
jsonInput.beginArray();
I toReturn = supplier.get();
Consumer<Object> consumer = consumerFactory.apply(toReturn);
Consumer<@Nullable Object> consumer = consumerFactory.apply(toReturn);
while (jsonInput.hasNext()) {
consumer.accept(coercer.coerce(jsonInput, valueType, setting));
}
Expand Down
5 changes: 4 additions & 1 deletion java/src/org/openqa/selenium/json/ConstructorCoercer.java
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Expand Up @@ -126,7 +126,9 @@ public BiFunction<JsonInput, PropertySetting, Object> apply(Type type) {
List<ConstructorCandidate> candidates = getConstructorCandidates(type);

return (jsonInput, setting) -> {
Map<String, Object> properties = coercer.coerce(jsonInput, Json.MAP_TYPE, setting);
Map<String, Object> properties =
Require.nonNull(
"Properties for " + type, coercer.coerce(jsonInput, Json.MAP_TYPE, setting));
ConstructorCandidate candidate = findConstructor(type, candidates, properties.keySet());

return candidate.create(type, properties, setting);
Expand Down Expand Up @@ -228,6 +230,7 @@ private Map<String, Integer> getParameterIndexes(Parameter[] parameters) {
return indexes;
}

@Nullable
private Object coerceValue(Object value, Type type, PropertySetting setting) {
StringWriter rawJson = new StringWriter();
try (JsonOutput output = new JsonOutput(rawJson)) {
Comment on lines +233 to 236

@qodo-code-review qodo-code-review Bot Aug 23, 2026

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Remediation recommended

2. Nullable param typed nonnull 🐞 Bug ≡ Correctness

ConstructorCoercer.coerceValue is now annotated as returning @Nullable, but its value
parameter remains non-null even though callers pass properties.get(...) which can be null,
creating a nullness-contract violation and warnings under @NullMarked.
Agent Prompt 
### Issue description
`coerceValue` can be invoked with `null` (when the JSON map contains a key with a `null` value), but its signature requires a non-null `Object value`.

### Issue Context
This is in `org.openqa.selenium.json` which is `@NullMarked`, so unannotated parameters are non-null by default. The body already handles `null` correctly by writing it as JSON and re-coercing.

### Fix Focus Areas
- java/src/org/openqa/selenium/json/ConstructorCoercer.java[233-242]
- java/src/org/openqa/selenium/json/ConstructorCoercer.java[285-293]

### Suggested change
Update the signature to `private Object coerceValue(@Nullable Object value, Type type, PropertySetting setting)` (keeping the existing `@Nullable` return annotation).

ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools

Expand Down
2 changes: 1 addition & 1 deletion java/src/org/openqa/selenium/json/EnumCoercer.java
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Expand Up @@ -22,7 +22,7 @@
import java.lang.reflect.Type;
import java.util.function.BiFunction;

public class EnumCoercer<T extends Enum> extends TypeCoercer<T> {
public class EnumCoercer<T extends Enum<T>> extends TypeCoercer<T> {
Comment thread
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@Override
public boolean test(Class<?> aClass) {
Expand Down
13 changes: 7 additions & 6 deletions java/src/org/openqa/selenium/json/InstanceCoercer.java
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Expand Up @@ -32,6 +32,7 @@
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.stream.Stream;
import org.jspecify.annotations.Nullable;
import org.openqa.selenium.internal.Require;

class InstanceCoercer extends TypeCoercer<Object> {
Expand Down Expand Up @@ -168,9 +169,9 @@ private static Class<?> getClss(Type type) {

private static class TypeAndWriter {
private final Type type;
private final BiConsumer<Object, Object> writer;
private final BiConsumer<Object, @Nullable Object> writer;

TypeAndWriter(Type type, BiConsumer<Object, Object> writer) {
TypeAndWriter(Type type, BiConsumer<Object, @Nullable Object> writer) {
this.type = type;
this.writer = writer;
}
Expand All @@ -189,15 +190,15 @@ public TypeAndWriter apply(Field field) {
}
}

private static class FieldWriter implements BiConsumer<Object, Object> {
private static class FieldWriter implements BiConsumer<Object, @Nullable Object> {
private final Field field;

FieldWriter(Field field) {
this.field = field;
}

@Override
public void accept(Object instance, Object value) {
public void accept(Object instance, @Nullable Object value) {
try {
field.set(instance, value);
} catch (IllegalAccessException e) {
Expand Down Expand Up @@ -226,7 +227,7 @@ public TypeAndWriter apply(SimplePropertyDescriptor desc) {
}
}

private static class SimplePropertyWriter implements BiConsumer<Object, Object> {
private static class SimplePropertyWriter implements BiConsumer<Object, @Nullable Object> {
private final SimplePropertyDescriptor desc;
private final Method method;

Expand All @@ -236,7 +237,7 @@ private static class SimplePropertyWriter implements BiConsumer<Object, Object>
}

@Override
public void accept(Object instance, Object value) {
public void accept(Object instance, @Nullable Object value) {
method.setAccessible(true);
try {
method.invoke(instance, value);
Expand Down
4 changes: 2 additions & 2 deletions java/src/org/openqa/selenium/json/JsonInput.java
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Expand Up @@ -540,8 +540,8 @@ public <T> T readMapElement(String key) {
* @throws JsonException if coercion of the next element to the specified type fails
* @throws UncheckedIOException if an I/O exception is encountered
*/
public <T> List<T> readArray(Type type) {
List<T> toReturn = new ArrayList<>();
public <T> List<@Nullable T> readArray(Type type) {
List<@Nullable T> toReturn = new ArrayList<>();

beginArray();
while (hasNext()) {
Expand Down
6 changes: 2 additions & 4 deletions java/src/org/openqa/selenium/json/JsonTypeCoercer.java
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Expand Up @@ -37,6 +37,7 @@
import java.util.function.BiFunction;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import org.jspecify.annotations.Nullable;
import org.openqa.selenium.Capabilities;
import org.openqa.selenium.MutableCapabilities;
import org.openqa.selenium.internal.Require;
Expand Down Expand Up @@ -113,11 +114,8 @@ private JsonTypeCoercer(Stream<TypeCoercer<?>> coercers) {
(caps) -> ((k, v) -> caps.setCapability((String) k, v))));

// Container types
//noinspection unchecked
builder.add(new CollectionCoercer<>(List.class, this, ArrayList::new, (list) -> list::add));
//noinspection unchecked
builder.add(new CollectionCoercer<>(Set.class, this, HashSet::new, (set) -> set::add));
//noinspection unchecked
builder.add(
new CollectionCoercer<>(
Collection.class, this, ArrayList::new, (collection) -> collection::add));
Expand All @@ -139,7 +137,7 @@ private JsonTypeCoercer(Stream<TypeCoercer<?>> coercers) {
this.coercers = Collections.unmodifiableSet(builder);
}

<T> T coerce(JsonInput json, Type typeOfT, PropertySetting setter) {
<T> @Nullable T coerce(JsonInput json, Type typeOfT, PropertySetting setter) {
BiFunction<JsonInput, PropertySetting, Object> coercer =
knownCoercers.computeIfAbsent(typeOfT, this::buildCoercer);

Expand Down
11 changes: 7 additions & 4 deletions java/src/org/openqa/selenium/json/MapCoercer.java
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Expand Up @@ -17,25 +17,28 @@

package org.openqa.selenium.json;

import static java.util.Objects.requireNonNull;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Supplier;
import org.jspecify.annotations.Nullable;

class MapCoercer<T, I extends T> extends TypeCoercer<T> {

private final Class<T> stereotype;
private final JsonTypeCoercer coercer;
private final Supplier<I> supplier;
private final Function<I, BiConsumer<Object, Object>> consumerFactory;
private final Function<I, BiConsumer<Object, @Nullable Object>> consumerFactory;

public MapCoercer(
Class<T> stereotype,
JsonTypeCoercer coercer,
Supplier<I> supplier,
Function<I, BiConsumer<Object, Object>> consumerFactory) {
Function<I, BiConsumer<Object, @Nullable Object>> consumerFactory) {
this.stereotype = stereotype;
this.coercer = coercer;
this.supplier = supplier;
Expand Down Expand Up @@ -66,7 +69,7 @@ public BiFunction<JsonInput, PropertySetting, T> apply(Type type) {
return (jsonInput, setting) -> {
jsonInput.beginObject();
I toReturn = supplier.get();
BiConsumer<Object, Object> consumer = consumerFactory.apply(toReturn);
BiConsumer<Object, @Nullable Object> consumer = consumerFactory.apply(toReturn);
// JSON should always have a string key, so we can take the fastpath
boolean stringKey = String.class.equals(keyType);

Expand All @@ -76,7 +79,7 @@ public BiFunction<JsonInput, PropertySetting, T> apply(Type type) {
if (stringKey) {
key = jsonInput.nextName();
} else {
key = coercer.coerce(jsonInput, keyType, setting);
key = requireNonNull(coercer.coerce(jsonInput, keyType, setting));
}
Object value = coercer.coerce(jsonInput, valueType, setting);

Expand Down
3 changes: 2 additions & 1 deletion java/src/org/openqa/selenium/json/ObjectCoercer.java
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Expand Up @@ -20,6 +20,7 @@
import java.lang.reflect.Type;
import java.util.List;
import java.util.function.BiFunction;
import org.jspecify.annotations.Nullable;
import org.openqa.selenium.internal.Require;

class ObjectCoercer extends TypeCoercer<Object> {
Expand All @@ -36,7 +37,7 @@ public boolean test(Class type) {
}

@Override
public BiFunction<JsonInput, PropertySetting, Object> apply(Type type) {
public BiFunction<JsonInput, PropertySetting, @Nullable Object> apply(Type type) {
return (jsonInput, setting) -> {
Type target;

Expand Down
6 changes: 4 additions & 2 deletions java/src/org/openqa/selenium/json/TypeCoercer.java
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Expand Up @@ -21,13 +21,15 @@
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Predicate;
import org.jspecify.annotations.Nullable;

public abstract class TypeCoercer<T>
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implements Predicate<Class<?>>, Function<Type, BiFunction<JsonInput, PropertySetting, T>> {
implements Predicate<Class<?>>,
Function<Type, BiFunction<JsonInput, PropertySetting, @Nullable T>> {

@Override
public abstract boolean test(Class<?> aClass);

@Override
public abstract BiFunction<JsonInput, PropertySetting, T> apply(Type type);
public abstract BiFunction<JsonInput, PropertySetting, @Nullable T> apply(Type type);
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}
19 changes: 15 additions & 4 deletions java/test/org/openqa/selenium/json/JsonInputTest.java
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Expand Up @@ -39,7 +39,6 @@
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringReader;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.stream.Collectors;
Expand Down Expand Up @@ -234,7 +233,7 @@ void shouldDecodeUnicodeEscapesProperly() {
String raw = "{\"text\": \"\\u003Chtml\"}";

try (JsonInput in = new JsonInput(new StringReader(raw), new JsonTypeCoercer(), BY_NAME)) {
Map<String, Object> map = in.read(MAP_TYPE);
Map<String, Object> map = in.readMap();

assertThat(map.get("text")).isEqualTo("<html");
}
Expand All @@ -245,7 +244,8 @@ void shouldCallFromJsonWithJsonInputParameter() {
String raw = "{\"message\": \"Cheese!\"}";

try (JsonInput in = new JsonInput(new StringReader(raw), new JsonTypeCoercer(), BY_NAME)) {
HasFromJsonWithJsonInputParameter obj = in.read(HasFromJsonWithJsonInputParameter.class);
HasFromJsonWithJsonInputParameter obj =
in.readNonNull(HasFromJsonWithJsonInputParameter.class);

assertThat(obj.getMessage()).isEqualTo("Cheese!");
}
Expand All @@ -256,12 +256,23 @@ void canReadListOfType() {
String raw = " [ 1 , 2 , 3 , 4 ] ";

try (JsonInput in = new JsonInput(new StringReader(raw), new JsonTypeCoercer(), BY_NAME)) {
List<Integer> array = in.readArray(Integer.class);
var array = in.readArray(Integer.class);

assertThat(array).containsExactly(1, 2, 3, 4);
}
}

@Test
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void canReadListOfType_null() {
String raw = "[null, null]";

try (JsonInput in = new JsonInput(new StringReader(raw), new JsonTypeCoercer(), BY_NAME)) {
var array = in.readArray(Integer.class);

assertThat(array).containsExactly(null, null);
}
}

@Test
void shouldBeAbleToReadDataLongerThanReadBuffer() {
char[] chars = new char[] {'c', 'h', 'e', 's'};
Expand Down
7 changes: 7 additions & 0 deletions java/test/org/openqa/selenium/json/JsonTest.java
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Expand Up @@ -167,6 +167,13 @@ void canConstructASimpleString() {
assertThat(text).isEqualTo("cheese");
}

@Test
void toTypeReturnsNullForTopLevelJsonNull() {
String text = new Json().toType("null", String.class);

assertThat(text).isNull();
Comment on lines +171 to +174

@qodo-code-review qodo-code-review Bot Aug 23, 2026

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Remediation recommended

1. Nullable assigned to nonnull 🐞 Bug ⚙ Maintainability

In a @NullMarked package, the new test assigns a value it expects to be null into a non-null
String, contradicting the nullness contract and triggering nullness-checker/IDE warnings in the
test itself.
Agent Prompt 
### Issue description
`JsonTest.toTypeReturnsNullForTopLevelJsonNull` assigns a value it asserts is `null` into a non-null `String` within the `org.openqa.selenium.json` package, which is `@NullMarked`.

### Issue Context
This PR’s goal is to surface nullability correctly; tests should follow the same contract to avoid introducing warnings/errors into the build.

### Fix Focus Areas
- java/test/org/openqa/selenium/json/JsonTest.java[170-175]
- java/src/org/openqa/selenium/json/package-info.java[18-21]

### Suggested change
Change `String text = ...` to `@Nullable String text = ...` (or equivalent) so the test matches the intended nullability.

ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools

}

@Test
void canPopulateAMap() {
String raw = "{\"cheese\": \"brie\", \"foodstuff\": \"cheese\"}";
Expand Down
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