how to fix sql query plan hash value

Hi,

I have observed that one of production database query plan hash value changed from good execution plan to bad one.

I want to change the sql plan hash value to good one. How can I achieve that

PLAN_TABLE_OUTPUT

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SQL_ID b6k5jmmz5qq4y

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SELECT ENT_ID, ENT_NAME FROM ENTITY_MASTER,ENTITY_PRIVILEGE_MAPPING

WHERE ENT_ID = EPM_ENT_ID AND ENT_TYPE = 'CL' AND Ent_Status = 'E' AND

ENT_TEMPLET_CLIENT = 'Y' AND EPM_SEG_EQUITY = DECODE(:1,'Y','Y','N')

AND EPM_SEG_DERIVATIVES = DECODE(:2,'Y','Y','N') AND EPM_SEG_CF =