Bug: ConsulConfigSource.loadAllConfig() doesn't handle null return from getValues()

[sfloess]

Description

ConsulConfigSource.loadAllConfig() calls kvClient.getValues() and iterates over the result without checking if it's null. The Consul library may return null if the key prefix doesn't exist, causing NPE.

Location

jplatform-config-consul/src/main/java/org/flossware/jplatform/config/consul/ConsulConfigSource.java:229-244

Current Code

private void loadAllConfig() {
    try {
        KeyValueClient kvClient = consul.keyValueClient();
        List<Value> values = kvClient.getValues(config.getKeyPrefix());  // May return null!
        
        for (Value value : values) {  // NPE if values is null!
            if (value.getValueAsString().isPresent()) {
                String fullKey = value.getKey();
                String key = extractKey(fullKey);
                String val = value.getValueAsString().get();
                configCache.put(key, val);
            }
        }
    } catch (Exception e) {
        logger.warn("Failed to load config from Consul", e);
    }
}

Problem

From Consul Java client library documentation, getValues() can return null if:

• Key prefix doesn't exist in Consul
• Consul returns empty result

// First time starting with empty Consul
ConsulConfigSource source = new ConsulConfigSource(config);
source.start();  // Calls loadAllConfig()

// If keyPrefix doesn't exist in Consul:
// kvClient.getValues(config.getKeyPrefix()) returns null
// for (Value value : null) throws NPE!
// Caught by outer try-catch, logged as warning
// But configCache remains empty - silent failure!

Impact

• NPE when Consul has no keys under the prefix
• Silent failure - just logged as warning
• Empty config cache even if some configs should exist
• Poor error handling for first-time setup
• Confusing behavior for users

Fix

private void loadAllConfig() {
    try {
        KeyValueClient kvClient = consul.keyValueClient();
        List<Value> values = kvClient.getValues(config.getKeyPrefix());
        
        if (values == null || values.isEmpty()) {
            logger.info("No configuration found at prefix: {}", config.getKeyPrefix());
            return;
        }
        
        for (Value value : values) {
            if (value.getValueAsString().isPresent()) {
                String fullKey = value.getKey();
                String key = extractKey(fullKey);
                String val = value.getValueAsString().get();
                configCache.put(key, val);
            }
        }
        
        logger.debug("Loaded {} config entries from Consul", configCache.size());
    } catch (Exception e) {
        logger.warn("Failed to load config from Consul", e);
    }
}

[sfloess]

Fixed in commit b9c2a4f: Added null/empty check for getValues() return.