[Connectors] Ballerina not reading connector info from .balx files properly

[pubudu91]

There is an issue when reading .balx files and building the program model again. The connector info doesn't seem to be setting properly and it results in a null pointer exception being thrown at Java level. This issue is related to issue #3134 and PR #3176. Sample Ballerina code is given below:

import ballerina.lang.system;

function main (string[] args) {
	string test = testConnectorReturn("Pubudu", 26);
	system:println(test);

	string test2 = testConnectorReturnFromAction("Pubudu");
	system:println(test2);
}

connector Foo (string name, int age) {
    int userAge = 10 + age;
    string userName = "Ballerina" + name;

    action getUserName () (string) {
        return userName;
    }

    action getAge () (int) {
        return userAge;
    }
}

connector Bar (string name) {
    string userName = name;

    action returnConnectorFromAction () (Foo) {
        Foo foo = create Foo(userName, 1);
        return foo;
    }
}

function getFooConnector(string name, int age) (Foo) {
    Foo foo = create Foo(name, age);
    return foo;
}

function testConnectorReturn (string name, int age) (string) {
    Foo conn = getFooConnector(name, age);
    string userName = conn.getUserName();
    int userAge = conn.getAge();
    return "Username: " + userName + ", Age: " + userAge;
}

function testConnectorReturnFromAction (string name) (string) {
    Bar barCon = create Bar(name);
    Foo fooCon = barCon.returnConnectorFromAction();
    string userName = fooCon.getUserName();
    int userAge = fooCon.getAge();
    return "Username: " + userName + ", Age: " + userAge;
}

The error logged in the bre.log:

[2017-08-18 10:30:18,971]  ERROR {org.ballerinalang.launcher.Main} - ballerina: ballerina: invalid program file format 
org.ballerinalang.util.exceptions.ProgramFileFormatException: ballerina: invalid program file format
	at org.ballerinalang.BLangProgramLoader.read(BLangProgramLoader.java:52)
	at org.ballerinalang.launcher.LauncherUtils.runProgram(LauncherUtils.java:57)
	at org.ballerinalang.launcher.Main$RunCmd.execute(Main.java:233)
	at java.util.Optional.ifPresent(Optional.java:159)
	at org.ballerinalang.launcher.Main.main(Main.java:42)
Caused by: java.lang.NullPointerException
	at org.ballerinalang.util.codegen.ProgramFileReader.createBTypeFromSig(ProgramFileReader.java:791)
	at org.ballerinalang.util.codegen.ProgramFileReader.getParamTypes(ProgramFileReader.java:721)
	at org.ballerinalang.util.codegen.ProgramFileReader.setCallableUnitSignature(ProgramFileReader.java:712)
	at org.ballerinalang.util.codegen.ProgramFileReader.readConnectorInfoEntries(ProgramFileReader.java:462)
	at org.ballerinalang.util.codegen.ProgramFileReader.readPackageInfo(ProgramFileReader.java:337)
	at org.ballerinalang.util.codegen.ProgramFileReader.readProgramInternal(ProgramFileReader.java:135)
	at org.ballerinalang.util.codegen.ProgramFileReader.readProgram(ProgramFileReader.java:109)
	at org.ballerinalang.BLangProgramLoader.read(BLangProgramLoader.java:45)
	... 4 more