elastic/elasticsearch · error · NullPointerException

${name} ${description} was null

Error message

${name} ${description} was null

What it means

AbstractLazyPropertyCollection is the base for Gradle lazy property containers (e.g. dependency/module lists). assertNotNull is called by subclasses when normalising their collection; if a caller passed null for a required element the method throws a NullPointerException naming the collection, the description of the offending argument, and the owner being configured if known.

Source

Thrown at build-tools/src/main/java/org/elasticsearch/gradle/AbstractLazyPropertyCollection.java:31

public abstract class AbstractLazyPropertyCollection {

    final String name;
    final Object owner;

    public AbstractLazyPropertyCollection(String name) {
        this(name, null);
    }

    public AbstractLazyPropertyCollection(String name, Object owner) {
        this.name = name;
        this.owner = owner;
    }

    public abstract List<? extends Object> getNormalizedCollection();

    void assertNotNull(Object value, String description) {
        if (value == null) {
            throw new NullPointerException(name + " " + description + " was null" + (owner != null ? " when configuring " + owner : ""));
        }
    }

}

View on GitHub (pinned to db6a809a66)

Solutions

1. Read the message: it states which collection and which description was null, plus the owner.
2. Filter or default the value before adding: `Optional.ofNullable(x).ifPresent(coll::add)`.
3. Fix the upstream provider so it never supplies null — set a convention or use a Property.

Example fix

// before
collection.add(maybeNullProvider.getOrNull())
// after
Optional.ofNullable(maybeNullProvider.getOrNull()).ifPresent(collection::add)

static <T> void addIfPresent(AbstractLazyPropertyCollection coll, T value, String description) {
    if (value == null) {
        throw new NullPointerException(coll + " " + description + " was null");
    }
    // coll.add(value) — guarded
}

static <T> boolean isAddable(T value) {
    return value != null;
}

try {
    collection.add(value);
} catch (NullPointerException npe) {
    if (npe.getMessage().contains("was null")) {
        getLogger().warn("Skipping null element: {}", npe.getMessage());
    } else { throw npe; }
}

When it happens

Trigger: Invoking an add/with method on a lazy collection subclass with a null element while the subclass delegates through assertNotNull(value, description). The owner context is appended only when the collection was constructed with an owner.

Common situations: A build plugin call like dependencies.add(null) or a convention that forwards a possibly-null provider value; a refactor that removed a provider's convention without a fallback; a third-party plugin integrating with ES build tools passing null.

Related errors

• Elasticsearch version is missing from properties.
• Expected elasticsearch version to be numbers only of the for
• Invalid qualifier: ${qualifier}
• build.snapshot was set to [${buildSnapshotSystemProperty}] b
• Sysprop [${property}] must be [true] or [false] but was [${p

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/5ada4a889ec83acc. Report an issue: GitHub.