google-rfc-2445 is a Java implementation of RFC 2445 recurrence rules. RFC 2445 describes a scheme for calendar interoperability. This project implements core parts of RFC 2445, including a parser for recurrence rules and date lists and a mechanism for evaluating recurrence rules.
gradle-sablecc-plugin is a gradle plugin which creates parsers using SableCC. SableCC supports automatic CST-to-AST transformation, emits all the visitor patterns and analysis helpers you will likely ever need, and is LR, not LL(k). Many example grammars are available for modern languages; the author of this plugin has written dozens.
hotpotato (or hptt, for short) is a high performance and throughput oriented HTTP client Java library, with support for HTTP 1.1 pipelining. It was developed mostly towards server-side usage, where speed and low resource usage are the key factors, but it can be used to build client applications as well. Built on top of Netty and designed for high concurrency scenarios where multiple threads can use the same instance of a client without any worries for external or internal synchronization, hotpotato helps you reduce initialization and/or preparation times and resource squandering. Among many small optimizations, connections are reused whenever possible, which results in a severe reduction of total request execution times by cutting connection establishment overhead.