apache/beam · error · RuntimeException

Setter has wrong prefix <method>

Error message

Setter has wrong prefix <method>

What it means

Thrown by FieldValueTypeInformation.forSetter when a method expected to be a setter does not start with the configured setterPrefix (default "set"). The prefix is stripped to derive the property name, so a mismatching name cannot be mapped.

Source

Thrown at sdks/java/core/src/main/java/org/apache/beam/sdk/schemas/FieldValueTypeInformation.java:291

    return forSetter(null, method);
  }

  public static FieldValueTypeInformation forSetter(Method method, String setterPrefix) {
    return forSetter(null, method, setterPrefix);
  }

  public static FieldValueTypeInformation forSetter(
      @Nullable TypeDescriptor<?> typeDescriptor, Method method) {
    return forSetter(typeDescriptor, method, "set");
  }

  public static FieldValueTypeInformation forSetter(
      @Nullable TypeDescriptor<?> typeDescriptor, Method method, String setterPrefix) {
    String name;
    if (method.getName().startsWith(setterPrefix)) {
      name = ReflectUtils.stripPrefix(method.getName(), setterPrefix);
    } else {
      throw new RuntimeException("Setter has wrong prefix " + method.getName());
    }

    TypeDescriptor<?> type =
        Optional.ofNullable(typeDescriptor)
            .map(td -> (TypeDescriptor) td.resolveType(method.getGenericParameterTypes()[0]))
            // fall back to previous behavior
            .orElseGet(() -> TypeDescriptor.of(method.getGenericParameterTypes()[0]));
    boolean nullable = hasSingleNullableParameter(method);
    return new AutoValue_FieldValueTypeInformation.Builder()
        .setName(name)
        .setNullable(nullable)
        .setType(type)
        .setRawType(type.getRawType())
        .setMethod(method)
        .setElementType(getIterableComponentType(type))
        .setMapKeyType(getMapKeyType(type))
        .setMapValueType(getMapValueType(type))
        .setOneOfTypes(Collections.emptyMap())

View on GitHub (pinned to 12126d8942)

Solutions

1. Rename the method to start with the setterPrefix in use (default "set").
2. Pass the correct setterPrefix to JavaBeanSchema/forSetter to match the class convention (e.g. "with" for builders).
3. Use @SchemaFieldName-style annotations on getters and let mapping match setters by property name.

Example fix

// before (schema uses "set" prefix)
public User withName(String name) { ... }

// after
public User setName(String name) { ... }

String prefix = "set"; for (Method m : clazz.getMethods()) { if (m.getParameterCount() == 1 && !m.getName().startsWith(prefix)) { /* flag non-setter single-arg methods or fix prefix */ } }

static boolean matchesSetterPrefix(Method m, String prefix) { return m.getName().startsWith(prefix) && m.getParameterCount() == 1; }

try { schemaOf(clazz); } catch (RuntimeException e) { if (e.getMessage().startsWith("Setter has wrong prefix")) { /* align method names with setterPrefix */ } else { throw e; } }

When it happens

Trigger: Schema registration with a custom setter prefix (e.g. "with") while methods use "set", or vice versa; passing a non-setter method to forSetter.

Common situations: Builder-style classes using withX/prefix conventions being registered with default "set" prefix; custom setterPrefix string mismatch (case or trailing characters).

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• Getter has wrong prefix <method>
• Setter methods should take a single argument <method>
• @SchemaFieldNumber can only be used on getters in Java Beans
• @SchemaFieldName can only be used on getters in Java Beans.
• Could not determine array parameter type for field.

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/5c3c70eafa024035. Report an issue: GitHub.