Use of the keyword 'volatile' is generally used to fine tune a Java application, and therefore, requires a good expertise of the Java Memory Model. Moreover, its range of action is somewhat misknown. Therefore, the volatile keyword should not be used for maintenance purpose and portability. AvoidUsingVolatile (Priority: 1, Ruleset: Multithreading) https://docs.pmd-code.org/snapshot/pmd_rules_java_multithreading.html#avoidusingvolatile

Use of the keyword 'volatile' is generally used to fine tune a Java application, and therefore, requires a good expertise of the Java Memory Model. Moreover, its range of action is somewhat misknown. Therefore, the volatile keyword should not be used for maintenance purpose and portability. AvoidUsingVolatile (Priority: 1, Ruleset: Multithreading) https://docs.pmd-code.org/snapshot/pmd_rules_java_multithreading.html#avoidusingvolatile

Ensure that resources (like `java.sql.Connection`, `java.sql.Statement`, and `java.sql.ResultSet` objects and any subtype of `java.lang.AutoCloseable`) are always closed after use. Failing to do so might result in resource leaks. Note: It suffices to configure the super type, e.g. `java.lang.AutoCloseable`, so that this rule automatically triggers on any subtype (e.g. `java.io.FileInputStream`). Additionally specifying `java.sql.Connection` helps in detecting the types, if the type resolution / auxclasspath is not correctly setup. Note: Since PMD 6.16.0 the default value for the property `types` contains `java.lang.AutoCloseable` and detects now cases where the standard `java.io.*Stream` classes are involved. In order to restore the old behaviour, just remove "AutoCloseable" from the types. The property `allowedResourceMethodPatterns` can be used to specify method invocation patterns that return resources which are managed externally and don't need to be closed by the caller. This is useful for servlet-related streams like `HttpServletRequest.getReader()` or `HttpServletResponse.getWriter()`, which are managed by the servlet container. The patterns use InvocationMatcher syntax (e.g., `javax.servlet.ServletRequest#getReader()`). CloseResource (Priority: 1, Ruleset: Error Prone) https://docs.pmd-code.org/snapshot/pmd_rules_java_errorprone.html#closeresource