I'm trying to use NiFi expression language with a custom property on the ExtractText processor. It appears that the ExtractText processor interprets the value literally and does not interpolate the value. Is there a way to achieve this?         java.util.regex.PatternSyntaxException: Illegal repetition near index 2 ${start} ^ at java.base/java.util.regex.Pattern.error(Pattern.java:2028) at java.base/java.util.regex.Pattern.closure(Pattern.java:3374) at java.base/java.util.regex.Pattern.sequence(Pattern.java:2229) at java.base/java.util.regex.Pattern.expr(Pattern.java:2069) at java.base/java.util.regex.Pattern.compile(Pattern.java:1783) at java.base/java.util.regex.Pattern.<init>(Pattern.java:1430) at java.base/java.util.regex.Pattern.compile(Pattern.java:1095) at org.apache.nifi.processors.standard.ExtractText.onScheduled(ExtractText.java:366) at jdk.internal.reflect.GeneratedMethodAccessor483.invoke(Unknown Source) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:564) at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:145) at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:133) at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:78) at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotation(ReflectionUtils.java:55) at org.apache.nifi.controller.StandardProcessorNode.lambda$initiateStart$4(StandardProcessorNode.java:1582) at org.apache.nifi.engine.FlowEngine$3.call(FlowEngine.java:123) at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) at java.base/java.lang.Thread.run(Thread.java:832) ... View more