theonedev/onedev · error · ValidationException

Duplicate values not allowed

Error message

Duplicate values not allowed

What it means

Thrown by ParamUtils.validateParamValues when the same value combination (List<String>) appears more than once for a parameter. Duplicates are meaningless for a value matrix and would create ambiguous param instances, so validation rejects them. validateParamMatrix wraps this with the param name for context.

Source

Thrown at server-core/src/main/java/io/onedev/server/buildspec/param/ParamUtils.java:38

import org.jspecify.annotations.Nullable;
import javax.validation.ValidationException;
import java.io.Serializable;
import java.util.*;
import java.util.stream.Collectors;

public class ParamUtils {
	
	private static final Logger logger = LoggerFactory.getLogger(ParamInstances.class);
	
	private static final String PARAM_BEAN_CLASS_NAME_PREFIX = "BuildParamBean";
	
	public static void validateParamValues(List<List<String>> values) {
		if (values.isEmpty())
			throw new ValidationException("At least one value needs to be specified");
		Set<List<String>> encountered = new HashSet<>();
		for (List<String> value: values) {
			if (encountered.contains(value)) 
				throw new ValidationException("Duplicate values not allowed");
			else 
				encountered.add(value);
		}
	}
	
	private static void validateParamMatrix(List<ParamSpec> paramSpecs, Map<String, List<List<String>>> paramMatrix) {
		Map<String, ParamSpec> paramSpecMap = ParamUtils.getParamSpecMap(paramSpecs);
		validateParamNames(paramSpecMap.keySet(), paramMatrix.keySet());
		for (Map.Entry<String, List<List<String>>> entry: paramMatrix.entrySet()) {
			if (entry.getValue() != null) {
				try {
					validateParamValues(entry.getValue());
				} catch (ValidationException e) {
					String errorMessage = String.format("Error validating param values (param: %s, error message: %s)", 
							entry.getKey(), e.getMessage());
					throw new ValidationException(errorMessage);
				}

View on GitHub (pinned to d44925c47c)

Solutions

  1. Remove the duplicate value row so each combination is unique
  2. If multiple params share values, use one row with multiple columns instead of repeated rows
  3. Deduplicate programmatically before calling validateParamValues

Example fix

// before
values: [["1.0"], ["1.0"]]
// after
values: [["1.0"], ["2.0"]]
Defensive patterns

Strategy: validation

Validate before calling

Set<List<String>> seen = new HashSet<>();
for (List<String> row : values)
    if (!seen.add(row)) throw new IllegalArgumentException("duplicate value combination: " + row);

Try / catch

try { ParamUtils.validateParamValues(values); } catch (ValidationException e) { /* deduplicate and retry */ }

Prevention

When it happens

Trigger: Calling validateParamValues with a list containing two identical List<String> entries, e.g. values [["a"],["a"]], typically from SpecifiedValues in a BuildSpec.

Common situations: Copy-pasting a value row in the YAML or in the job parameter form; merging param lists from two sources; UI allowing repeated rows.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

AI-assisted analysis of theonedev/onedev@d44925c47c (2026-09-06). Data as JSON: /api/errors/9df32e21404385b0. Report an issue: GitHub.