PackagePrintStream.java

import org.jetbrains.annotations.Nullable;

import java.io.OutputStream;
import java.io.PrintStream;
import java.io.UnsupportedEncodingException;

public class PackagePrintStream extends PrintStream {

  public PackagePrintStream(OutputStream out, boolean autoFlush, String encoding) throws UnsupportedEncodingException {
    super(out, autoFlush, encoding);
  }

  @Override
  public void println(@Nullable String x) {
    if (allow()) {
      super.println(x);
    }
  }

  private boolean allow() {
    String cn = inferCaller().getClassName();
    return !cn.startsWith("org.springframework.cloud.function.context.catalog.SimpleFunctionRegistry$FunctionInvocationWrapper");
  }

  private boolean isPrintImplFrame(String cname) {
    return PackagePrintStream.class.getName().equals(cname);
  }

  private StackTraceElement inferCaller() {
    StackTraceElement stack[] = (new Throwable()).getStackTrace();
    int ix = 0;
    while (ix < stack.length) {
      StackTraceElement frame = stack[ix];
      String cname = frame.getClassName();
      if (isPrintImplFrame(cname)) {
        break;
      }
      ix++;
    }

    while (ix < stack.length) {
      StackTraceElement frame = stack[ix];
      String cname = frame.getClassName();
      if (!isPrintImplFrame(cname)) {
        return frame;
      }
      ix++;
    }

    return new StackTraceElement(PackagePrintStream.class.getName(), "write",
      PackagePrintStream.class.getName(), -1);
  }
}

Usage.java

  // https://github.com/spring-cloud/spring-cloud-function/issues/962
  static {
    try {
      System.setOut(new PackagePrintStream(System.out, true, "UTF-8"));
    } catch (UnsupportedEncodingException e) {
      throw new RuntimeException(e);
    }
  }