Twitter Source Working and Documentation

**Describe the bug**
Twitter source never retrieves messages. Perhaps change in twitter api.

Also documentation is missing two key values

e: https://github.com/apache/pulsar/blob/master/pulsar-io/twitter/src/main/java/org/apache/pulsar/io/twitter/TwitterFireHoseConfig.java
@FieldDoc(
required = false,
defaultValue = "",
help = "A comma separated list of user IDs, indicating the users to return statuses for in the stream."
)
private String followings;
@FieldDoc(
required = false,
defaultValue = "",
help = "Keywords to track. Phrases of keywords are specified by a comma-separated list."
)
private String terms;

[TwitterFireHoseConfig.java](https://github.com/apache/pulsar/blob/master/pulsar-io/twitter/src/main/java/org/apache/pulsar/io/twitter/TwitterFireHoseConfig.java)

**To Reproduce**

**Expected behavior**
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**Screenshots**
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**Desktop (please complete the following information):**
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**Additional context**
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Start with pulsar-io/twitter/src/main/java/org/apache/pulsar/io/twitter/TwitterFireHoseConfig.java and inspect how the Twitter source uses its configuration. Verify why the source no longer retrieves messages, then ensure the documentation includes the followings and terms values shown in that file. Done means the source behavior is understood or corrected and both configuration values are documented.

Written by the indexing model from the issue text.