apache/maven · error · IllegalArgumentException

Multiple lower bounds not supported: {}

Error message

Multiple lower bounds not supported: {}

What it means

Error "Multiple lower bounds not supported: {}" thrown in apache/maven.

Source

Thrown at impl/maven-di/src/main/java/org/apache/maven/di/impl/Types.java:343

            throw new IllegalArgumentException("Key should not contain a type variable: " + original);
        }

        if (original instanceof WildcardType wildcardType) {
            Type[] upperBounds = wildcardType.getUpperBounds();
            if (upperBounds.length == 1) {
                Type upperBound = upperBounds[0];
                if (upperBound != Object.class) {
                    return simplifyType(upperBound);
                }
            } else if (upperBounds.length > 1) {
                throw new IllegalArgumentException("Multiple upper bounds not supported: " + original);
            }

            Type[] lowerBounds = wildcardType.getLowerBounds();
            if (lowerBounds.length == 1) {
                return simplifyType(lowerBounds[0]);
            } else if (lowerBounds.length > 1) {
                throw new IllegalArgumentException("Multiple lower bounds not supported: " + original);
            }
            return Object.class;
        }

        return original;
    }

    private static Type[] simplifyTypes(Type[] original) {
        int length = original.length;
        for (int i = 0; i < length; i++) {
            Type typeArgument = original[i];
            Type repackTypeArgument = simplifyType(typeArgument);
            if (repackTypeArgument != typeArgument) {
                Type[] repackedTypeArguments = new Type[length];
                System.arraycopy(original, 0, repackedTypeArguments, 0, i);
                repackedTypeArguments[i++] = repackTypeArgument;
                for (; i < length; i++) {
                    repackedTypeArguments[i] = simplifyType(original[i]);

View on GitHub (pinned to e4093d4e12)

When it happens

Trigger: Thrown at impl/maven-di/src/main/java/org/apache/maven/di/impl/Types.java:343 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/e1547da5d055d222. Report an issue: GitHub.