question: private static void GetStringUTFRegion ( JNIEnvironment env , int strJREF , int start , int len , Address buf ) { if ( traceJNI ) VM . sysWrite ( "JNI called: GetStringUTFRegion \n" ) ; RuntimeEntrypoints . checkJNICountDownToGC ( ) ; try { String str = ( String ) env . getJNIRef ( strJREF ) ; String region = str . substring ( start , start + len ) ; int utflen = UTF8Convert . utfLength ( region ) + 1 ; JNIGenericHelpers . createUTFForCFromString ( region , buf , utflen ) ; } catch ( Throwable unexpected ) { if ( traceJNI ) unexpected . printStackTrace ( System . err ) ; env . recordException ( unexpected ) ; } }
target:  GetStringUTFRegion:  Copy a region of Unicode characters from a string to the given buffer, as UTF8 characters.