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  <xsd:element name="AssetAcquisitionsMeasurementInputDiscountRate" id="olp_AssetAcquisitionsMeasurementInputDiscountRate" type="xbrli:decimalItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="OperatingLeaseLeaseIncomeLeasePaymentsExcludingAmortizationRelatedToLeaseIntangibleAssetsAndLiabilities" id="olp_OperatingLeaseLeaseIncomeLeasePaymentsExcludingAmortizationRelatedToLeaseIntangibleAssetsAndLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
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  <xsd:element name="PerformanceCriteriaAverageAnnualTotalStockholderReturnPercentage" id="olp_PerformanceCriteriaAverageAnnualTotalStockholderReturnPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="July12022Member" id="olp_July12022Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="UnamortizedMortgageIntangibleAssets" id="olp_UnamortizedMortgageIntangibleAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="LongTermDebtFiscalYearMaturityPrincipalAndInterestAbstract" id="olp_LongTermDebtFiscalYearMaturityPrincipalAndInterestAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="SecuredDebtBeforeNettingOfDeferredFinancingCostsAmortizationPaymentsDueInYearTwo" id="olp_SecuredDebtBeforeNettingOfDeferredFinancingCostsAmortizationPaymentsDueInYearTwo" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="SecuredDebtBeforeNettingOfDeferredFinancingCostsAmortizationPaymentsDueInYearThree" id="olp_SecuredDebtBeforeNettingOfDeferredFinancingCostsAmortizationPaymentsDueInYearThree" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="SecuredDebtBeforeNettingOfDeferredFinancingCostsAmortizationPaymentsDueInYearFour" id="olp_SecuredDebtBeforeNettingOfDeferredFinancingCostsAmortizationPaymentsDueInYearFour" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
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  <xsd:element name="SecuredDebtBeforeNettingOfDeferredFinancingCostsAmortizationPaymentsDueAfterYearFive" id="olp_SecuredDebtBeforeNettingOfDeferredFinancingCostsAmortizationPaymentsDueAfterYearFive" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
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  <xsd:element name="SecuredDebtBeforeNettingOfDeferredFinancingCostsPrincipalBalloonPayments" id="olp_SecuredDebtBeforeNettingOfDeferredFinancingCostsPrincipalBalloonPayments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
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  <xsd:element name="SecuredDebtBeforeNettingOfDeferredFinancingCostsRepaymentsDueInYearTwo" id="olp_SecuredDebtBeforeNettingOfDeferredFinancingCostsRepaymentsDueInYearTwo" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
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  <xsd:element name="LineOfCreditFacilityRemainingCapacityAvailableForRenovationAndOperatingExpensePurposes" id="olp_LineOfCreditFacilityRemainingCapacityAvailableForRenovationAndOperatingExpensePurposes" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
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  <xsd:element name="AwardsGrantedIn2023Member" id="olp_AwardsGrantedIn2023Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="SaleOfRealEstateOtherAssetsAndReceivables" id="olp_SaleOfRealEstateOtherAssetsAndReceivables" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
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  <xsd:element name="LandLocatedInLakewoodColoradoMember" id="olp_LandLocatedInLakewoodColoradoMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
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  <xsd:element name="MortgagesEstimatedAmountToBePrepaidOnCompletionOfSaleOfProperty" id="olp_MortgagesEstimatedAmountToBePrepaidOnCompletionOfSaleOfProperty" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
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  <xsd:element name="DateOfAwardJuly162024Member" id="olp_DateOfAwardJuly162024Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="HootersRestaurantPropertyConcordNorthCarolinaMember" id="olp_HootersRestaurantPropertyConcordNorthCarolinaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="WriteOffNetUnamortizedIntangibleLeaseAssets" id="olp_WriteOffNetUnamortizedIntangibleLeaseAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="AwardsGrantedIn2022To2024Member" id="olp_AwardsGrantedIn2022To2024Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="NoncontrollingInterestShareOfGainLoss" id="olp_NoncontrollingInterestShareOfGainLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
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  <xsd:element name="LeaseBuyOutTransactionIndustrialTenantMember" id="olp_LeaseBuyOutTransactionIndustrialTenantMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="WriteOffUnamortizedIntangibleLeaseLiabilitiesNetOfWriteOffOfUnbilledRentReceivable" id="olp_WriteOffUnamortizedIntangibleLeaseLiabilitiesNetOfWriteOffOfUnbilledRentReceivable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ExpectedGainLossOnDispositionOfRealEstate" id="olp_ExpectedGainLossOnDispositionOfRealEstate" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="SaleOfPropertyExpectedGrossSalesPrice" id="olp_SaleOfPropertyExpectedGrossSalesPrice" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
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  <xsd:element name="AwardsGrantedIn2023To2025Member" id="olp_AwardsGrantedIn2023To2025Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="VacantRetailPropertyInCaryNorthCarolinaMember" id="olp_VacantRetailPropertyInCaryNorthCarolinaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="RealEstateAcquisitionsIn2026Member" id="olp_RealEstateAcquisitionsIn2026Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="RetailPropertyInSouthEuclidOhioMember" id="olp_RetailPropertyInSouthEuclidOhioMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="NumberOfIndustrialTenantsInLeaseBuyOutTransactions" id="olp_NumberOfIndustrialTenantsInLeaseBuyOutTransactions" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="MondelezGlobalLlcIndustrialPropertyInGreensboroNorthCarolinaMember" id="olp_MondelezGlobalLlcIndustrialPropertyInGreensboroNorthCarolinaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="MondelezGlobalLlcIndustrialPropertyInWestColumbiaSouthCarolinaMember" id="olp_MondelezGlobalLlcIndustrialPropertyInWestColumbiaSouthCarolinaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="MondelezGlobalLlcIndustrialPropertyInOmahaNebraskaMember" id="olp_MondelezGlobalLlcIndustrialPropertyInOmahaNebraskaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="MondelezGlobalLlcIndustrialPropertyInBirminghamAlabamaMember" id="olp_MondelezGlobalLlcIndustrialPropertyInBirminghamAlabamaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="HusqvarnaU.s.HoldingInc.IndustrialPropertyInBlythewoodSouthCarolinaMember" id="olp_HusqvarnaU.s.HoldingInc.IndustrialPropertyInBlythewoodSouthCarolinaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="BimboBakeriesInc.IndustrialPropertyInRichlandMississippiMember" id="olp_BimboBakeriesInc.IndustrialPropertyInRichlandMississippiMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="HabeUsaInc.IndustrialPropertyInRichlandMississippiMember" id="olp_HabeUsaInc.IndustrialPropertyInRichlandMississippiMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="OwensAndMinorDistributionInc.IndustrialPropertyInRichlandMississippiMember" id="olp_OwensAndMinorDistributionInc.IndustrialPropertyInRichlandMississippiMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="LandInBlythewoodSouthCarolinaMember" id="olp_LandInBlythewoodSouthCarolinaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="HavertysRetailPropertyInNewportNewsVirginiaMember" id="olp_HavertysRetailPropertyInNewportNewsVirginiaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="MultiTenantPropertyInChampaignIllinoisMember" id="olp_MultiTenantPropertyInChampaignIllinoisMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="MultiTenantRetailPropertyInElPasoTexasMember" id="olp_MultiTenantRetailPropertyInElPasoTexasMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="AbcSupplyInteriorsInc.OklahomaCityOklahomaMember" id="olp_AbcSupplyInteriorsInc.OklahomaCityOklahomaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="AbcSupplyInteriorsInc.SpanishForkUtahMember" id="olp_AbcSupplyInteriorsInc.SpanishForkUtahMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="NonCashPaymentOfOrdinaryDividendsCommonStock" id="olp_NonCashPaymentOfOrdinaryDividendsCommonStock" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
</xsd:schema>
