test: add comprehensive vectorizer provider tests

- Add VectorizerProviderIntegrationTest with 27+ tests
- Test all 9 providers: OpenAI, Azure OpenAI, Cohere, HuggingFace,
  Mistral AI, Vertex AI, Voyage AI, AWS Bedrock, Custom
- Tests include single/batch embedding, caching, error handling
- Use reflection for optional provider dependencies
- Tests skip gracefully when API keys not set

docs: enhance vectorizer documentation

- Add complete examples for all 9 LangChain4J providers
- Add Maven dependencies for each provider
- Add caching examples with EmbeddingsCache
- Add custom vectorizer implementation guide
- Add provider comparison table
- Fix embedMany -> embedBatch method calls
- Add preprocessing examples

All providers tested and documented:
✅ OpenAI (text-embedding-3-small, 1536 dims)
✅ Azure OpenAI (text-embedding-ada-002, 1536 dims)
✅ Cohere (embed-english-v3.0, 1024 dims)
✅ HuggingFace Remote API (all-MiniLM-L6-v2, 384 dims)
✅ Mistral AI (mistral-embed, 1024 dims)
✅ Vertex AI (textembedding-gecko@003, 768 dims)
✅ Voyage AI (voyage-large-2, 1536 dims)
✅ AWS Bedrock (amazon.titan-embed-text-v2:0, 1024 dims)
✅ Custom vectorizers (extend BaseVectorizer)

Author: bsbodden

.gitignore

@@ -46,6 +46,20 @@ build/
 compile_debug.log
 docs/.cache/*
 reports/*
+### Security - API Keys and Secrets ###
+# Never commit API keys, tokens, or credentials
+*.env
+.env
+.env.*
+!.env.example
+config.properties
+secrets.properties
+application-local.properties
+application-secrets.yml
+credentials.json
+api-keys.txt
+
+# Notebook environment files
 notebooks/.env
 
 ### JupyterNotebooks ###

core/src/main/java/com/redis/vl/exceptions/RedisVLException.java

@@ -5,10 +5,21 @@ public class RedisVLException extends RuntimeException {
 
   private static final long serialVersionUID = 1L;
 
+  /**
+   * Constructs a new RedisVLException with the specified detail message.
+   *
+   * @param message the detail message
+   */
   public RedisVLException(String message) {
     super(message);
   }
 
+  /**
+   * Constructs a new RedisVLException with the specified detail message and cause.
+   *
+   * @param message the detail message
+   * @param cause the cause of the exception
+   */
   public RedisVLException(String message, Throwable cause) {
     super(message, cause);
   }

core/src/main/java/com/redis/vl/extensions/ExtensionConstants.java

@@ -4,33 +4,68 @@
 public final class ExtensionConstants {
 
   // BaseMessageHistory
+  /** Field name for message entry ID. */
   public static final String ID_FIELD_NAME = "entry_id";
+
+  /** Field name for message role (e.g., user, assistant, system). */
   public static final String ROLE_FIELD_NAME = "role";
+
+  /** Field name for message content. */
   public static final String CONTENT_FIELD_NAME = "content";
+
+  /** Field name for tool call ID. */
   public static final String TOOL_FIELD_NAME = "tool_call_id";
+
+  /** Field name for message timestamp. */
   public static final String TIMESTAMP_FIELD_NAME = "timestamp";
+
+  /** Field name for session tag. */
   public static final String SESSION_FIELD_NAME = "session_tag";
 
   // SemanticMessageHistory
+  /** Field name for message vector field in semantic message history. */
   public static final String MESSAGE_VECTOR_FIELD_NAME = "vector_field";
 
   // SemanticCache
+  /** Field name for Redis key in semantic cache. */
   public static final String REDIS_KEY_FIELD_NAME = "key";
+
+  /** Field name for cache entry ID. */
   public static final String ENTRY_ID_FIELD_NAME = "entry_id";
+
+  /** Field name for prompt text in cache. */
   public static final String PROMPT_FIELD_NAME = "prompt";
+
+  /** Field name for response text in cache. */
   public static final String RESPONSE_FIELD_NAME = "response";
+
+  /** Field name for prompt vector in cache. */
   public static final String CACHE_VECTOR_FIELD_NAME = "prompt_vector";
+
+  /** Field name for cache insertion timestamp. */
   public static final String INSERTED_AT_FIELD_NAME = "inserted_at";
+
+  /** Field name for cache update timestamp. */
   public static final String UPDATED_AT_FIELD_NAME = "updated_at";
-  public static final String METADATA_FIELD_NAME = "metadata"; // also used in MessageHistory
+
+  /** Field name for metadata (used in both MessageHistory and SemanticCache). */
+  public static final String METADATA_FIELD_NAME = "metadata";
 
   // EmbeddingsCache
+  /** Field name for text in embeddings cache. */
   public static final String TEXT_FIELD_NAME = "text";
+
+  /** Field name for model name in embeddings cache. */
   public static final String MODEL_NAME_FIELD_NAME = "model_name";
+
+  /** Field name for embedding vector. */
   public static final String EMBEDDING_FIELD_NAME = "embedding";
+
+  /** Field name for embedding dimensions. */
   public static final String DIMENSIONS_FIELD_NAME = "dimensions";
 
   // SemanticRouter
+  /** Field name for route vector in semantic router. */
   public static final String ROUTE_VECTOR_FIELD_NAME = "vector";
 
   private ExtensionConstants() {

core/src/main/java/com/redis/vl/extensions/cache/BaseCache.java

@@ -10,9 +10,16 @@
 /** Abstract base class for all cache implementations. */
 public abstract class BaseCache {
 
+  /** The name of the cache. */
   protected final String name;
+
+  /** The Redis key prefix for this cache. */
   protected final String prefix;
+
+  /** Default time-to-live in seconds for cache entries. */
   protected Integer ttl;
+
+  /** The Redis client connection. */
   protected UnifiedJedis redisClient;
 
   /**
@@ -36,7 +43,12 @@ protected BaseCache(String name, UnifiedJedis redisClient, Integer ttl) {
     this.ttl = ttl;
   }
 
-  /** Creates a new BaseCache instance without TTL. */
+  /**
+   * Creates a new BaseCache instance without TTL.
+   *
+   * @param name The name of the cache
+   * @param redisClient The Redis client connection
+   */
   protected BaseCache(String name, UnifiedJedis redisClient) {
     this(name, redisClient, null);
   }
@@ -151,7 +163,13 @@ public void disconnect() {
     }
   }
 
-  /** Helper method to set a value with optional TTL. */
+  /**
+   * Helper method to set a value with optional TTL.
+   *
+   * @param key The cache key
+   * @param value The value to store
+   * @param ttl Time-to-live in seconds (null uses default TTL)
+   */
   protected void setWithTtl(String key, String value, Integer ttl) {
     SetParams params = new SetParams();
     Integer effectiveTtl = ttl != null ? ttl : this.ttl;
@@ -161,7 +179,13 @@ protected void setWithTtl(String key, String value, Integer ttl) {
     redisClient.set(key, value, params);
   }
 
-  /** Helper method to set a byte array value with optional TTL. */
+  /**
+   * Helper method to set a byte array value with optional TTL.
+   *
+   * @param key The cache key as byte array
+   * @param value The value as byte array
+   * @param ttl Time-to-live in seconds (null uses default TTL)
+   */
   protected void setWithTtl(byte[] key, byte[] value, Integer ttl) {
     if (ttl != null || this.ttl != null) {
       Integer effectiveTtl = ttl != null ? ttl : this.ttl;

core/src/main/java/com/redis/vl/extensions/cache/EmbeddingsCache.java

@@ -33,7 +33,12 @@ public EmbeddingsCache(String name, UnifiedJedis redisClient, Integer ttl) {
     super(name, redisClient, ttl);
   }
 
-  /** Creates a new EmbeddingsCache instance without TTL. */
+  /**
+   * Creates a new EmbeddingsCache instance without TTL.
+   *
+   * @param name The name of the cache
+   * @param redisClient The Redis client connection
+   */
   public EmbeddingsCache(String name, UnifiedJedis redisClient) {
     this(name, redisClient, null);
   }

core/src/main/java/com/redis/vl/extensions/cache/SemanticCache.java

@@ -497,31 +497,71 @@ public static class Builder {
     private float distanceThreshold = 0.2f;
     private Integer ttl;
 
+    /** Create a new Builder instance */
+    public Builder() {
+      // Default constructor
+    }
+
+    /**
+     * Set the cache name
+     *
+     * @param name Cache name
+     * @return This builder
+     */
     public Builder name(String name) {
       this.name = name;
       return this;
     }
 
+    /**
+     * Set the Redis client
+     *
+     * @param redisClient UnifiedJedis client
+     * @return This builder
+     */
     public Builder redisClient(UnifiedJedis redisClient) {
       this.redisClient = redisClient;
       return this;
     }
 
+    /**
+     * Set the vectorizer
+     *
+     * @param vectorizer Vectorizer to use for embedding prompts
+     * @return This builder
+     */
     public Builder vectorizer(BaseVectorizer vectorizer) {
       this.vectorizer = vectorizer;
       return this;
     }
 
+    /**
+     * Set the distance threshold for semantic similarity
+     *
+     * @param threshold Distance threshold (default: 0.2)
+     * @return This builder
+     */
     public Builder distanceThreshold(float threshold) {
       this.distanceThreshold = threshold;
       return this;
     }
 
+    /**
+     * Set the TTL for cache entries
+     *
+     * @param ttl Time-to-live in seconds
+     * @return This builder
+     */
     public Builder ttl(Integer ttl) {
       this.ttl = ttl;
       return this;
     }
 
+    /**
+     * Build the SemanticCache
+     *
+     * @return SemanticCache instance
+     */
     public SemanticCache build() {
       if (name == null || name.isEmpty()) {
         throw new IllegalArgumentException("Cache name is required");