code: @Nonnull
      public BugInstance addCalledMethod(ConstantPoolGen cpg, InvokeInstruction inv) {
          String className = inv.getClassName(cpg);
          String methodName = inv.getMethodName(cpg);
          String methodSig = inv.getSignature(cpg);
          addMethod(className, methodName, methodSig, inv.getOpcode() == Const.INVOKESTATIC);
          describe(MethodAnnotation.METHOD_CALLED);
          return this;
      }
docs: Add a method annotation for the method which is called by given
  instruction.
  
  @param cpg
  the constant pool for the method containing the call
  @param inv
  the InvokeInstruction
  @return this object