Convert Object List Into Map : <p>I have list of objects which have two properties {alpha,beta} as below :</p>

<pre><code>obj1 = {alpha1,beta1}
obj2 = {alpha2,beta2}
obj3 = {alpha3,beta3}
obj3 = {alpha1,beta2}
obj5 = {alpha3,beta1}
</code></pre>

<p>I want to create a map such as <code>Map&lt;alphaKey,List&lt;beta&gt;&gt;</code></p>

<p>so It will like below :</p>

<pre><code>alpha1 --&gt; beta1,beta2
alpha2 --&gt; beta2
alpha3 --&gt; beta3,beta1
</code></pre>

<p>Thanks</p>
