code: @Nullable
      private UCPMUserValue callHasInline(int seen) {
          if (seen != Const.INVOKEVIRTUAL) {
              return null;
          }
  
          String sig = getSigConstantOperand();
          String returnSig = SignatureUtils.getReturnSignature(sig);
          if (Values.SIG_JAVA_UTIL_STRINGBUILDER.equals(returnSig) || Values.SIG_JAVA_UTIL_STRINGBUFFER.equals(returnSig)) {
              int parmCount = SignatureUtils.getNumParameters(sig);
              if (stack.getStackDepth() > parmCount) {
                  OpcodeStack.Item itm = stack.getStackItem(parmCount);
                  return (UCPMUserValue) itm.getUserValue();
              }
          }
  
          return null;
      }
docs: checks to see if the current opcode is an INVOKEVIRTUAL call that has a INLINE userValue on the caller and a return value. If so, return it.
  
  @param seen
  the currently parsed opcode
  @return whether the caller has an INLINE tag on it