apache/maven · error · IntrospectionException

The token '%s' at position '%d' refers to a java.util.List o

Error message

The token '%s' at position '%d' refers to a java.util.List or an array, but the value seems is an instance of '%s'

What it means

Error "The token '%s' at position '%d' refers to a java.util.List or an array, but the value seems is an instance of '%s'" thrown in apache/maven.

Source

Thrown at impl/maven-impl/src/main/java/org/apache/maven/impl/model/reflection/ReflectionValueExtractor.java:264

            int index = Integer.parseInt(indexStr);

            if (value.getClass().isArray()) {
                return Array.get(value, index);
            }

            if (value instanceof List list) {
                return list.get(index);
            }
        } catch (NumberFormatException | IndexOutOfBoundsException e) {
            return null;
        }

        final String message = String.format(
                "The token '%s' at position '%d' refers to a java.util.List or an array, but the value "
                        + "seems is an instance of '%s'",
                expression.subSequence(from, to), from, value.getClass());

        throw new IntrospectionException(message);
    }

    private static Object getPropertyValue(Object value, String property) throws IntrospectionException {
        if (value == null || property == null || property.isEmpty()) {
            return null;
        }

        ClassMap classMap = getClassMap(value.getClass());
        String methodBase = Character.toTitleCase(property.charAt(0)) + property.substring(1);
        try {
            for (String prefix : ACCESSOR_PREFIXES) {
                Method method = classMap.findMethod(prefix + methodBase);
                if (method != null) {
                    return method.invoke(value, OBJECT_ARGS);
                }
            }
            return null;
        } catch (InvocationTargetException e) {

View on GitHub (pinned to e4093d4e12)

When it happens

Trigger: Thrown at impl/maven-impl/src/main/java/org/apache/maven/impl/model/reflection/ReflectionValueExtractor.java:264 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/8c32418ba78ef796. Report an issue: GitHub.