core/src/main/java/com/google/cloud/sql/core/CoreSocketFactory.java
private boolean runningOnGaeStandard() {
    // gaeEnv="standard" indicates standard instances
    String gaeEnv = System.getenv("GAE_ENV");
    // runEnv="Production" requires to rule out Java 8 emulated environments
    String runEnv = System.getProperty("com.google.appengine.runtime.environment");
    // gaeRuntime="java11" in Java 11 environments (no emulated environments)
    String gaeRuntime = System.getenv("GAE_RUNTIME");

    return "standard".equals(gaeEnv)
        && ("Production".equals(runEnv) || "java11".equals(gaeRuntime));
  }
private boolean runningOnGaeStandard() {
    // gaeEnv="standard" indicates standard instances
    String gaeEnv = System.getenv("GAE_ENV");
    // runEnv="Production" requires to rule out Java 8 emulated environments
    String runEnv = System.getProperty("com.google.appengine.runtime.environment");
    // gaeRuntime="java11" in Java 11 environments (no emulated environments)
    String gaeRuntime = System.getenv("GAE_RUNTIME");

    return "standard".equals(gaeEnv)
        && ("Production".equals(runEnv) || "java11".equals(gaeRuntime));
  }
Returns {@code true} if running in a Google App Engine Standard runtime.