openzipkin/zipkin · error · NullPointerException

overrides == null

Error message

overrides == null

What it means

KafkaCollector.Builder.overrides(Map) throws NullPointerException when the map argument is null. Overrides let you replace any consumer config property (e.g. auto.offset.reset=latest) on top of the builder defaults; the guard is a simple null check before properties.putAll(overrides).

Source

Thrown at zipkin-collector/kafka/src/main/java/zipkin2/collector/kafka/KafkaCollector.java:126

    }

    /**
     * By default, a consumer will be built from properties derived from builder defaults, as well
     * as "auto.offset.reset" -> "earliest". Any properties set here will override the consumer
     * config.
     *
     * <p>For example: Only consume spans since you connected by setting the below.
     *
     * <pre>{@code
     * Map<String, String> overrides = new LinkedHashMap<>();
     * overrides.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "latest");
     * builder.overrides(overrides);
     * }</pre>
     *
     * @see org.apache.kafka.clients.consumer.ConsumerConfig
     */
    public final Builder overrides(Map<String, ?> overrides) {
      if (overrides == null) throw new NullPointerException("overrides == null");
      properties.putAll(overrides);
      return this;
    }

    @Override
    public KafkaCollector build() {
      return new KafkaCollector(this);
    }

    Builder() {
      // Settings below correspond to "New Consumer Configs"
      // https://kafka.apache.org/documentation/#newconsumerconfigs
      properties.put(GROUP_ID_CONFIG, "zipkin");
      properties.put(AUTO_OFFSET_RESET_CONFIG, "earliest");
      properties.put(KEY_DESERIALIZER_CLASS_CONFIG, ByteArrayDeserializer.class.getName());
      properties.put(VALUE_DESERIALIZER_CLASS_CONFIG, ByteArrayDeserializer.class.getName());
    }
  }

View on GitHub (pinned to 878ce2a1fa)

Solutions

1. Pass an empty map instead of null when no overrides are needed (an empty map is accepted; putAll is a no-op)
2. Guard the call: if (overrides != null) builder.overrides(overrides)
3. Fix the config loader to return an empty map by default

Example fix

// before
builder.overrides(config.getKafkaOverrides()); // returns null when section absent

// after
builder.overrides(config.getKafkaOverrides() != null
  ? config.getKafkaOverrides()
  : Collections.emptyMap());

Map<String, ?> overrides = config.kafkaOverrides();
if (overrides != null) builder.overrides(overrides);

static boolean hasOverrides(Map<String, ?> m) { return m != null && !m.isEmpty(); }

When it happens

Trigger: Calling .overrides(null), or passing a Map field that was never initialized (common when overrides are optional and the config loader returns null for a missing section).

Common situations: Treating overrides as optional: a config binding produces null when no overrides are defined, and the caller forwards it unconditionally.

Related errors

• bootstrapServers == null
• groupId == null
• serviceUrl is null or empty
• sessionFactory == null
• metrics == null

AI-assisted analysis of openzipkin/zipkin@878ce2a1fa (2026-08-14). Data as JSON: /api/errors/7518d9ab4f254762. Report an issue: GitHub.