flowable/flowable-engine · error · UnsupportedOperationException

org.flowable.cdi.impl.ProcessVariableMap.containsValue() is

Error message

org.flowable.cdi.impl.ProcessVariableMap.containsValue() is not supported.

What it means

ProcessVariableMap.containsValue(Object) throws UnsupportedOperationException unconditionally. Scanning all process variables by value would require full variable enumeration, which the map view does not implement.

Source

Thrown at modules/flowable-cdi/src/main/java/org/flowable/cdi/impl/ProcessVariableMap.java:77

    @Override
    public int size() {
        throw new UnsupportedOperationException(ProcessVariableMap.class.getName() + ".size() is not supported.");
    }

    @Override
    public boolean isEmpty() {
        throw new UnsupportedOperationException(ProcessVariableMap.class.getName() + ".isEmpty() is not supported.");
    }

    @Override
    public boolean containsKey(Object key) {
        throw new UnsupportedOperationException(ProcessVariableMap.class.getName() + ".containsKey() is not supported.");
    }

    @Override
    public boolean containsValue(Object value) {
        throw new UnsupportedOperationException(ProcessVariableMap.class.getName() + ".containsValue() is not supported.");
    }

    @Override
    public Object remove(Object key) {
        throw new UnsupportedOperationException("ProcessVariableMap.remove is unsupported. Use ProcessVariableMap.put(key, null)");
    }

    @Override
    public void clear() {
        throw new UnsupportedOperationException(ProcessVariableMap.class.getName() + ".clear() is not supported.");
    }

    @Override
    public Set<String> keySet() {
        throw new UnsupportedOperationException(ProcessVariableMap.class.getName() + ".keySet() is not supported.");
    }

    @Override

View on GitHub (pinned to d6d39ce1c6)

Solutions

Use get(name) for the specific variables you care about and compare values yourself.
Enumerate variables via the process engine query API instead of the CDI map.
Rewrite the check to be name-based rather than value-based.

Example fix

// before
boolean hasCustomer = processVariableMap.containsValue(customer);

// after
boolean hasCustomer = customer.equals(processVariableMap.get("customerVar"));

Defensive patterns

Strategy: validation

Validate before calling

// value lookup must be name-based
boolean hasCustomer = Objects.equals(customer, processVariableMap.get("customerVar"));

Try / catch

try { has = processVariableMap.containsValue(v); } catch (UnsupportedOperationException e) { /* fall back to per-name get comparisons */ }

Prevention

Design lookups around variable names, not values
Use engine variable queries for value-based searches
Do not use reverse-lookup Map helpers on this map

When it happens

Trigger: Calling containsValue(x) directly; helper libraries that use containsValue for reverse lookups or de-duplication before inserting into a Map.

Common situations: Generic code that prevents duplicate values across any Map; diagnostics code searching which variable holds a given value.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/5ddb7d281b590849. Report an issue: GitHub.