quarkusio/quarkus · error · IllegalArgumentException

map key null

Error message

map key null

What it means

UriBuilder.resolveTemplates(Map) throws IllegalArgumentException when the map contains a null key. Template variable names are the map keys, and a null key cannot correspond to any {placeholder} in the template, so it is rejected before resolution.

Source

Thrown at independent-projects/resteasy-reactive/common/runtime/src/main/java/org/jboss/resteasy/reactive/common/jaxrs/UriBuilderImpl.java:1096

    public String toTemplate() {
        return buildString(new HashMap<String, Object>(), true, true, true);
    }

    public UriBuilder resolveTemplate(String name, Object value) throws IllegalArgumentException {
        if (name == null)
            throw new IllegalArgumentException("Name is null");
        if (value == null)
            throw new IllegalArgumentException("Value is null");
        HashMap<String, Object> vals = new HashMap<String, Object>();
        vals.put(name, value);
        return resolveTemplates(vals);
    }

    public UriBuilder resolveTemplates(Map<String, Object> templateValues) throws IllegalArgumentException {
        if (templateValues == null)
            throw new IllegalArgumentException("Template values null");
        if (templateValues.containsKey(null))
            throw new IllegalArgumentException("map key null");
        return uriTemplate(buildCharSequence(templateValues, false, true, true));
    }

    public UriBuilder resolveTemplate(String name, Object value, boolean encodeSlashInPath) throws IllegalArgumentException {
        if (name == null)
            throw new IllegalArgumentException("Name is null");
        if (value == null)
            throw new IllegalArgumentException("Value is null");
        HashMap<String, Object> vals = new HashMap<String, Object>();
        vals.put(name, value);
        return uriTemplate(buildCharSequence(vals, false, true, encodeSlashInPath));
    }

    public UriBuilder resolveTemplateFromEncoded(String name, Object value) throws IllegalArgumentException {
        if (name == null)
            throw new IllegalArgumentException("Name is null");
        if (value == null)
            throw new IllegalArgumentException("Value is null");

View on GitHub (pinned to e1c734241f)

Solutions

1. Filter out null keys before calling: templateValues.keySet().removeIf(Objects::isNull) on a mutable copy
2. Fix the producer of the map so keys are always non-null
3. Validate keys when populating the map and throw a contextual error early

Example fix

// before
builder.resolveTemplates(params); // params.containsKey(null)
// after
Map<String, Object> safe = new HashMap<>(params);
safe.keySet().removeIf(Objects::isNull);
builder.resolveTemplates(safe);

for (String key : templateValues.keySet()) {
    if (key == null) {
        throw new IllegalArgumentException("template value map has a null key");
    }
}
uriBuilder.resolveTemplates(templateValues);

boolean hasNoNullKeys(Map<String, Object> m) {
    return m != null && !m.containsKey(null);
}

try {
    return uriBuilder.resolveTemplates(templateValues);
} catch (IllegalArgumentException e) {
    Map<String, Object> cleaned = new HashMap<>(templateValues);
    cleaned.keySet().removeIf(Objects::isNull);
    return uriBuilder.resolveTemplates(cleaned);
}

When it happens

Trigger: Passing a HashMap that a caller populated with a null key (HashMap permits null keys), e.g. map.put(null, value) — often from merging maps or reading keyed data where a key is missing.

Common situations: Merging several parameter maps where one is keyed by a nullable name; building the map from data where the 'name' column/field is null.

Related errors

• Template values null
• Name is null
• Segment is null
• Values is null
• Literal must not be null

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/5a7bb51060761ee6. Report an issue: GitHub.