apache/pulsar · error · IllegalArgumentException

unsupported field-type %s for %s

Error message

unsupported field-type %s for %s

What it means

FieldParser.value() only supports parameterized (generic) fields of type List, Set, Map, or Optional. Any other generic field type encountered while converting a non-blank string value throws IllegalArgumentException naming the field type and name.

Source

Thrown at pulsar-common/src/main/java/org/apache/pulsar/common/util/FieldParser.java:198

                return stringToList(strValue, clazz);
            } else if (field.getType().equals(Set.class)) {
                // covert to set
                return stringToSet(strValue, clazz);
            } else if (field.getType().equals(Map.class)) {
                Class<?> valueClass =
                    (Class<?>) ((ParameterizedType) field.getGenericType()).getActualTypeArguments()[1];
                return stringToMap(strValue, clazz, valueClass);
            } else if (field.getType().equals(Optional.class)) {
                Type typeClazz = ((ParameterizedType) fieldType).getActualTypeArguments()[0];
                if (typeClazz instanceof ParameterizedType) {
                    throw new IllegalArgumentException(format("unsupported non-primitive Optional<%s> for %s",
                            typeClazz.getClass(), field.getName()));
                }
                @SuppressWarnings("unchecked") // typeClazz is verified to be a non-parameterized Class
                Optional<?> result = Optional.ofNullable(convert(strValue, (Class<?>) typeClazz));
                return result;
            } else {
                throw new IllegalArgumentException(
                        format("unsupported field-type %s for %s", field.getType(), field.getName()));
            }
        } else {
            return convert(strValue, field.getType());
        }
    }

    /**
     * Sets the empty/null value if field is allowed to be set empty.
     *
     * @param strValue
     * @param field
     * @param obj
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     */
    public static <T> void setEmptyValue(String strValue, Field field, T obj)
            throws IllegalArgumentException, IllegalAccessException {

View on GitHub (pinned to 820761864e)

Solutions

1. Change the field to List<T>, Set<T>, Map<K,V>, or a simple type that convert() supports.
2. Parse the field manually and set it via direct assignment/setter instead of FieldParser.update().
3. Exclude the field from the properties map so update() never attempts to convert it.

Example fix

// before
private Properties extraProps; // unsupported field-type class java.util.Properties
// after
private Map<String, String> extraProps; // supported via stringToMap

static final Set<Class<?>> SUPPORTED_GENERIC = Set.of(List.class, Set.class, Map.class, Optional.class);
static void checkGenericType(Field f) {
    if (f.getGenericType() instanceof ParameterizedType && !SUPPORTED_GENERIC.contains(f.getType())) {
        throw new IllegalArgumentException("unsupported field-type " + f.getType() + " for " + f.getName());
    }
}

static boolean isFieldParserSupported(Field f) {
    if (!(f.getGenericType() instanceof ParameterizedType)) return true; // falls to convert()
    return List.class.equals(f.getType()) || Set.class.equals(f.getType())
            || Map.class.equals(f.getType()) || Optional.class.equals(f.getType());
}

try {
    return FieldParser.value(strValue, field);
} catch (IllegalArgumentException e) {
    if (e.getMessage().startsWith("unsupported field-type")) {
        return null; // or parse with Jackson manually
    }
    throw e;
}

When it happens

Trigger: Calling update()/value() on a class with a generic field whose raw type is not List/Set/Map/Optional, e.g. Properties props field, custom Collection<E> subclass, or OptionalInt-style types, when the properties map has a non-blank value for it.

Common situations: Config classes holding java.util.Properties or custom collection fields populated from a properties map; adding a new collection type to a Pulsar config class that FieldParser was never taught about.

Related errors

• unsupported non-primitive Optional<%s> for %s
• Failed to instantiate ${className}
• Exception caused while converting configuration: ${message}
• Failed to compute configuration overrides
• Failed to create authentication: ${message}

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/7795266dcd32003b. Report an issue: GitHub.