- **Logging Abstraction** (`org.codelibs.core.log`) - Flexible logging system supporting JCL (Jakarta Commons Logging) and JUL (Java Util Logging)
- **Concurrent Utilities** (`org.codelibs.core.concurrent`) - Thread-safe collections and concurrency helpers using modern concurrent APIs
- **Crypto & Security** (`org.codelibs.core.crypto`, `org.codelibs.core.security`) - Basic cryptographic utilities, message digest operations, and secure random generation

    }

    /**
     * Deletes a document from the specified index with optimistic concurrency control.
     *
     * @param index       the index name
     * @param id          the document ID
     * @param seqNo       the sequence number for optimistic concurrency control
     * @param primaryTerm the primary term for optimistic concurrency control
     * @return true if the document was deleted successfully, false otherwise