3.1.0_preview2: ClassFormatException: Constant pool at index 0 is null

[barney2k7]

While experimenting with 3.1.0_preview2, I noticed that findbugs/bcel fails to parse the following code during analysis. Note that this problem only occurs in the preview, fb 3.0.1 handles this code just fine. In case you're not interested in bug reports for previews, feel free to just close this issue.

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Properties;
import java.util.stream.Stream;

public class MyClass {
  
  public static void create(URL url) {
    try (InputStream in = url.openStream()) {
      Properties p1 = new Properties();
      p1.load(in);
    } catch (IOException e) {
    }
  }
  
  public Stream<String> keys() {
    return Stream.<Properties>of().flatMap(p -> p.stringPropertyNames().stream());
  }

}

Analysing this class e.g. in the findbugs gui results in the following stacktrace:

The following errors occurred during analysis:
  Exception analyzing MyClass using detector edu.umd.cs.findbugs.detect.FindUnsatisfiedObligation
    org.apache.bcel.classfile.ClassFormatException: Constant pool at index 0 is null.
      At org.apache.bcel.classfile.ConstantPool.getConstant(ConstantPool.java:258)
      At org.apache.bcel.classfile.ConstantPool.getConstantString(ConstantPool.java:293)
      At org.apache.bcel.generic.FieldOrMethod.getReferenceType(FieldOrMethod.java:116)
      At edu.umd.cs.findbugs.ba.obl.InstructionActionCache.getActions(InstructionActionCache.java:107)
      At edu.umd.cs.findbugs.ba.obl.ObligationAnalysis.transferInstruction(ObligationAnalysis.java:139)
      At edu.umd.cs.findbugs.ba.obl.ObligationAnalysis.transferInstruction(ObligationAnalysis.java:68)
      At edu.umd.cs.findbugs.ba.AbstractDataflowAnalysis.transfer(AbstractDataflowAnalysis.java:135)
      At edu.umd.cs.findbugs.ba.obl.ObligationAnalysis.transfer(ObligationAnalysis.java:160)
      At edu.umd.cs.findbugs.ba.obl.ObligationAnalysis.transfer(ObligationAnalysis.java:68)
      At edu.umd.cs.findbugs.ba.Dataflow.execute(Dataflow.java:376)
      At edu.umd.cs.findbugs.classfile.engine.bcel.ObligationDataflowFactory.analyze(ObligationDataflowFactory.java:75)
      At edu.umd.cs.findbugs.classfile.engine.bcel.ObligationDataflowFactory.analyze(ObligationDataflowFactory.java:45)
      At edu.umd.cs.findbugs.classfile.impl.AnalysisCache.analyzeMethod(AnalysisCache.java:369)
      At edu.umd.cs.findbugs.classfile.impl.AnalysisCache.getMethodAnalysis(AnalysisCache.java:322)
      At edu.umd.cs.findbugs.detect.FindUnsatisfiedObligation$MethodChecker.analyzeMethod(FindUnsatisfiedObligation.java:240)
      At edu.umd.cs.findbugs.detect.FindUnsatisfiedObligation.visitMethodCFG(FindUnsatisfiedObligation.java:158)
      At edu.umd.cs.findbugs.bcel.CFGDetector.visitClass(CFGDetector.java:93)
      At edu.umd.cs.findbugs.detect.FindUnsatisfiedObligation.visitClass(FindUnsatisfiedObligation.java:138)
      At edu.umd.cs.findbugs.FindBugs2.analyzeApplication(FindBugs2.java:1089)
      At edu.umd.cs.findbugs.FindBugs2.execute(FindBugs2.java:283)
      At edu.umd.cs.findbugs.gui2.BugLoader.doAnalysis(BugLoader.java:101)
      At edu.umd.cs.findbugs.gui2.AnalyzingDialog$AnalysisThread.run(AnalyzingDialog.java:275)

[iloveeclipse]

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